Answer
pOH = 4.1
Explanation
Given:
pH = 9.9
Required: The concentration of OH-
Solution
pH + pOH = 14
9.9 + pOH = 14
pOH = 14-9.9
pOH = 4.1
How many molecules are in 82.93 moles of N205?
Answer:
2.41 molecules.
Explanation:
hope this helps!
The reaction of carbon dioxide to form carbon monoxide and oxygen is what type of reaction?2CO2(g) → 2CO(g) + O2(g)decompositionoxidationcombinationsingle replacementdouble replacement
Answer
Decomposition
Explanation
2CO2(g) → 2CO(g) + O2(g)
The reaction of carbon dioxide to form carbon monoxide and oxygen as shown above is a decomposition reaction.
A decomposition reaction can be defined as a chemical reaction in which one reactant breaks down into two or more products.
In the reaction, a single reactant carbon dioxide breaks down or decomposes to form carbon monoxide and oxygen.
A gas is confined to a cylinder under constant atmospheric pressure.When 600J of heat IS added to the gas . It expands and does 140J of Work on the surroundings . What are the values of ∆H and ∆E.
As heat is being added, the value of q (that is equal to ∆H) is positive:
[tex]\Delta H=600\text{ J}[/tex]To find ∆E we need to calculate the difference between ∆H and w (work):
[tex]\Delta E=600J-140J=460J[/tex]How many grams are in 1.5 x 1016 atoms of sulfur (S)?
A.
1.3 x 106grams
B.
8.0 x 10-7 grams
C.
7.9 x 10-8 grams
D.
2.9 x 1041 grams
Answer:
the answer is B
Explanation:
because i just choose the answer
is chalk made of calcium carbonate, CaCO3. explain which atoms are needed, and in what ratios, to make chalk. are the elements that make up chalk metals or nonmetal? what would you predict would happen when this substance is placed in water
Answer: calcium is metal and carbon and oxygen is non metal. If you place the chalk in the water there won’t be any chemical reaction
Explanation: Hope my answer is helpful
What do you notice about the average seismic wave speeds at a depth of 90 km in the locations where volcanoes have occurred? Does this support or refute the idea that the heat for volcanic magma is a deep feature?
The average seismic wave speeds at a depth of 90 km in volcanic areas, They typically travel at speeds ranging from 1 to 14 km/h. The slower values represent a P-wave traveling in water, while the higher numbers represent a P-wave speed near the Earth's mantle's core.
How fast do seismic waves travel?The average seismic wave speeds at a depth of 90 km in volcanic areas, They typically travel at speeds ranging from 1 to 14 km/h. The slower values represent a P-wave traveling in water, while the higher numbers represent a P-wave speed near the Earth's mantle's core.Seismic velocities are affected by the material properties of the media through which seismic waves pass, such as composition, mineral phase and packing structure, temperature, and pressure. Seismic waves travel faster through denser materials and, as a result, travel faster with depth.Both earthquake epicenters and volcanoes are located in the same area. Earthquakes do not occur at random on the earth's surface. They are typically concentrated in small areas. Some are near the edges of continents, others are in mid-continents, and still others are in oceans.To learn more about : Seismic waves
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Calculate the enthalpy change for the reaction P4O6(s)+2O2(g)→P4O10(s)
given the following enthalpies of reaction:
P4(s)+3O2(g)→P4O6(s)ΔH=−1640.1kJ
P4(s)+5O2(g)→P4O10(s)ΔH=−2940.1kJ
Considering the Hess's Law, the enthalpy change for the reaction P₄O₆ (s) + 2 O₂ (g) → P₄O₁₀ (s) is -1300 kJ.
Definition of Hess's LawHess's Law indicates that the enthalpy change in a chemical reaction will be the same whether it occurs in a single stage or in several stages. That is, the sum of the ∆H of each stage of the reaction will give us a value equal to the ∆H of the reaction when it occurs in a single stage.
Enthalpy change in this caseIn this case you want to calculate the enthalpy change of:
P₄O₆ (s) + 2 O₂ (g) → P₄O₁₀ (s)
which occurs in two stages.
You know the following reactions, with their corresponding enthalpies:
Equation 1: P₄(s) + 3 O₂(g) → P₄O₆ (s) ΔH = -1640.1 kJ
Equation 2: P₄(s) + 5 O₂(g) → P₄O₁₀ (s) ΔH = -2940.1 kJ
Because of the way formation reactions are defined, any chemical reaction can be written as a combination of formation reactions, some going forward and some going back.
First, to obtain the enthalpy of the desired chemical reaction you need one mole of P₄O₆ on reactant side and it is present in first equation on the product side. So it is necessary to locate the P₄O₆ on the reactant side (invert it). When an equation is inverted, the sign of delta H also changes.
Now, you need one mole of P₄O₁₀ on product side and it is present in second equation so let's write this as such.
In summary, you know that two equations with their corresponding enthalpies are:
Equation 1: P₄O₆ (s) → P₄(s) + 3 O₂(g) ΔH = 1640.1 kJ
Equation 2: P₄(s) + 5 O₂(g) → P₄O₁₀ (s) ΔH = -2940.1 kJ
Adding or canceling the reactants and products as appropriate, and adding the enthalpies algebraically, you obtain:
P₄O₆ (s) + 2 O₂ (g) → P₄O₁₀ (s) ΔH= -1300 kJ
Finally, the enthalpy change in this case is -1300 kJ.
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Cinnamon owes its flavor and odor to cinnamaldehyde (C9H8O). Determine the boiling point elevation of a solution of 97.1 mg of cinnamaldehyde dissolved in 1.00 g of carbon tetrachloride (Kb = 5.03°C/m).______ °C
Step 1
The equation for the boiling point elevation used here:
[tex]\Delta Tb\text{ = Kb x m }[/tex]m = molality, which is calculated as follows:
[tex]m\text{ = }\frac{moles\text{ of solute}}{Mass\text{ of solvent \lparen kg\rparen}}[/tex]Kb = boiling constant
-------------------------
Step 2
Information provided:
Solute = C9H8O
Solvent = carbon tetrachloride
Mass of solute = 97.1 mg
(1 g = 1000 mg => 97.1 mg x (1 g/1000 mg) = 0.0971 g)
Mass of solvent = 1.00 g
(1 kg = 1000 g => 1.00 g x (1 kg/1000 g) = 1x10^-3 kg)
---
Information needed:
The molar mass of solute = 132.1 g/mol (please, the periodic table is useful here)
-------------------------
Step 3
The number of moles of solute: n
n = mass of solute/the molar mass of solute = 0.0971 g/ 132.1 g/mol = 7.35x10^-4 moles
----
Molality, m:
m = moles of solute/mass of solvent (kg) = 7.35x10^-4 moles/1x10^-3 kg = 0.735 moles/kg or m
----
The boiling point elevation:
ΔTb = Kb x m = 5.03 °C/m x 0.735 m = 3.69 °C
Answer: ΔTb = 3.69 °C
1. SEP Develop Models Use the space to create a model of the investigative
phenomenon. As you develop your model, consider the following:
• Why are fireworks different colors? What features of the atomic structure
might be part of the reasoning? How is light made or moved?
• Your model does not need to include every feature of the phenomenon.
Instead, focus on the features that you think are important for explaining
how or why the phenomenon occurs.
•
Use labels to identify and differentiate the components of your model.
.
Choose an appropriate scale for the model. If needed, label any specific
dimensions or measurements.
An atom is a complicated configuration of negatively charged electrons grouped around a positively charged nucleus in certain shells. Protons and neutrons make up the majority of the atom's mass in this nucleus (except for common hydrogen which has only one proton).
Fireworks' vibrant colors come from mineral components. Bright greens are produced by barium, deep reds by strontium, blues by copper, and yellow by sodium.
What is Atomic structure ?For instance, the nucleus of hydrogen is made up of a positively charged proton and a negatively charged electron. On the periodic table of elements, the atomic structure is also depicted.Protons, electrons, and neutrons are the three fundamental particles that make up an atom. The protons (positively charged particles) and neutrons are found in the nucleus (center) of an atom (no charge). The electrons are located in the outermost portions of the atom, which are known as the electron shells (negatively charged).Types ;
The atomic theory of John Dalton.model for plum pudding.Atomic model proposed by Rutherford.Atomic model proposed by Bohr.Atomic Model Based on Quantum Mechanics and the Electron Cloud.The quantum mechanical atomic model is basic description:To know more about Atom please click here ; https://brainly.com/question/6258301
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What is the total number of atoms represented in
the formula below?
2Sr3(PO4)2
There are 30 atoms in 2Sr3(PO4)2.
In the given formula there are 2 molecules of Sr3(PO4)2.
To find the number of atoms in molecules by looking at the molecular formula, we must count the presence of each atom in the molecule.
To calculate the total number of atoms, we first calculate the number of atoms for 2Sr3(PO4)2.
Number of Strontium atoms = 3*2 = 6
Number of Phosphorus atoms = 1*2*2 = 4
Number of Oxygen atoms = 4*2*2 = 16
Total number of atoms =6+4+16=30
So, there are 30 atoms in 2Sr3(PO4)2.
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Only this one question don’t need to write an entire goddam 15 sentences but just give me a correct answer
A given element must have the same number of protons as neutrons and electrons, this is not a requirement. No other element has an atom with two protons besides helium, which has two protons in every atom.
How do electrons work?An electrical force keeps electrons in their shells. An atom's protons and electrons are drawn to one another. They are both electrically charged. Electrons have a negative charge (-), while protons have a positive charge (+).
Where can you find electrons?Electrons are present outside the atom's nucleus, in contrast to protons and neutrons, which are contained inside the nucleus at its center. Negative electrons are drawn to the positive nucleus because the electric charges of opposite polarity attract one another.
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The complete question is -
Does a given element always have the same number of each particle? Why or why not? Using periodic table, give some specific examples.
What is the balanced chemical equation for the reaction used to calculate ΔH∘f of BaCO3(s) ?
The balanced equation that can be used to fond the heat of formation is;
[tex]Ba(s) + C(s) + \frac{3}{2}O_{2} (g) ----- > BaCO_{3} (s)[/tex]
What is the heat of formation?The heat of formation is defined as the heat that is evolved or absorbed when a substance is formed from its component elements under standard conditions. Note that the components of the equations must be the substances that are in standard form.
In this case, we are trying to see the balanced chemical equation for the reaction used to calculate ΔH∘f of BaCO3(s). We have to know that is equation must have to involved the barium, carbon and oxygen atoms as the barium carbonate compound is formed.
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What happens in a single-replacement reaction?
A single replacement reaction, also known as a single displacement reaction, occurs when one element in a molecule is swapped out for another. Starting ingredients are always pure elements combined with an aqueous compound, such as pure hydrogen gas or zinc metal.
Two pure elements and one aqueous compound or solution are required for all single-replacement reactions. The A and C in the aforementioned reaction would be pure elements. Zn + 2HCl > ZnCl2 + H2 is an example of a single-replacement reaction in detail.
You must make use of a "Activity Series" table to ascertain whether a certain single replacement will take place. A single displacement reaction will take place if the metal or halogen is above the element it would replace according to the activity series.
In a compound, one element takes the place of another to create a new material. The number of reactants and products in a single replacement reaction is equal.
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how many
times would you have to drive back and forth to
travel 186,000 miles
If you drove a car that got 30 miles per gallon, you would have to drive 6,200 miles to travel 186,000 miles.
What is travel?
Travel is the movement of people between geographically distant regions. Travel can be done on foot, bicycle, automobile, rail, boat, bus, airline, ship, or other mode of transportation, with or without luggage, and can be one way or round trip. As in the case of tourism, travel might sometimes include relatively short stops between subsequent movements. The meaning of the word "travel" is very certainly lost to history. The name "travel" may have sprung from the Old French word travail, which meant "labour." According to the Merriam-Webster dictionary, the word travel was first used in the 14th century.
If you drove a car that got 30 miles per gallon and you had a tank that held 20 gallons, you would have to drive 6,200 miles to use up a full tank of gas. You would need to drive back and forth 186,000 / 6,200 = 30 times to travel 186,000 miles.
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True or False *hint 3 Trues and only 1 false*
True or false, Meiosis starts with half the number of chromosomes as Mitosis.
True or false, the genetic offspring are exactly like the parent call.
True or false, there are 23 chromosomes from each parent cell.
True or false, meiosis goes through 2 stages of division, meiosis i and ii.
Meiosis starts with half the number of chromosomes as Mitosis = True
The genetic offspring are exactly like the parent call = False
There are 23 chromosomes from each parent cell = True
Meiosis goes through 2 stages of division, meiosis i and ii = True
---------------------------------------------------
Hope this helps!
Have a great day and God bless! :)
The Radium Girls experienced devastating health outcomes from ingesting radium from their paint brushes.
We know that both radium and calcium will concentrate in our bones. Why might this be, and why might
radium be damaging to our bones while calcium is not?
Choose ALL correct answers.
A Radium and calcium will both form 2+ cations but radium is more reactive and more unstable.
B Radium and calcium will both form 2+ anions but radium is more reactive and more unstable.
C Calcium and radium are period 2 elements. Both will concentrate in our bones due to their similar
chemical properties.
D Calcium and radium are group 2 elements. Both will concentrate in our bones due to their similar
chemical properties.
Both radium and calcium will concentrate on our bones. Suitable statements are A and D Calcium and radium are group 2 elements. Both will concentrate on our bones due to their similar chemical properties.
Radium and calcium are alkaline earth metals, meaning they proportion a number of equal chemical homes due to each in their atom's outer shells containing two valence electrons. although radium is radioactive and calcium isn't, the frame can't distinguish among these factors that appear to act in an identical manner.
The paint contained radium. even as radium is only faintly radioactive, the women were informed to lick their paintbrushes to present the finer points. This led to complaints that had been influential in the early levels of workplace safety law within the U.S.
Young ladies painted face dials with radioactive fabric. Unaware that the paint turned into dangerous, they would locate the brush tip on their lips to acquire a nice point. After being laid low with radium poisoning, numerous younger girls sued their employers and brought national attention to the safety of people.
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[tex] \huge \color{basic}{ \boxed{ \tt{✐Answer:}}}[/tex]
The Radium Girls experienced devastating health outcomes from ingesting radium from their paint brushes. We know that both radium and calcium will concentrate in our bones. Why might this be, and why might radium be damaging to our bones while calcium is not?
Choose ALL correct answers.
☑︎ A. Radium and calcium will both form 2+ cations but radium is more reactive and more unstable.
☐ B. Radium and calcium will both form 2+ anions but radium is more reactive and more unstable.
☐ C. Calcium and radium are period 2 elements. Both will concentrate in our bones due to their similar chemical properties.
☐ D. Calcium and radium are group 2 elements. Both will concentrate in our bones due to their similar chemical properties.
________________________________
The correct answer is letter [tex] \large \bold{A}[/tex]
Complete the equation for the dissociation of the electrolyte AgNO3(aq) . Omit water from the equation because it is understood to be present.
The equation of the dissociation of the compound is [tex]AgNO_{3} (s)---- > Ag^{+} (aq) + NO_{3^{-} (aq)[/tex]
What is dissociation?The term dissociation has to do with the process by which a substance is broken up into its constituents. Now we know that the electrolytes are composed of ions. These ions are the charge carriers that are responsible for the fact that the solution is able to be a conductor of the electric current as we know the electrolytes to be as usual.
We can now write the equation of the dissociation from the equation; [tex]AgNO_{3} (s)---- > Ag^{+} (aq) + NO_{3^{-} (aq)[/tex]. The water has been omitted as was instructed in the question.
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The equation for the dissociation of the electrolyte AgNO₃(aq) is:
[tex]\rm AgNO_3\rightarrow Ag ^+ + NO_3 ^-[/tex]
What is dissociation?Dissociation is defined as a broad process in which molecules (or ionic compounds like salts, or complexes) split or separate into different elements like atoms, ions, or radicals, typically in a reversible way.
We now know that ions make up the electrolytes. These ions are the charge carriers that make it possible for the solution to serve as a conductor of the electric current in the manner that we have come to expect from electrolytes.
Thus, the equation for the dissociation of the electrolyte AgNO₃(aq) is:
[tex]\rm AgNO_3\rightarrow Ag ^+ + NO_3 ^-[/tex]
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3. Which of these describes a chemical
change? sc.8.P.9.2
A baking cookies
B melting ice
C Cutting apple slices
D mowing the grass
Each of the following phrases matches one of the models below. Match the statement with its appropriate model.
Which scientist is known for developing the planetary model of the atom?
Answer: Neils Bohr
Explanation: Development of the Atomic Theory. In 1913, Neils Bohr, a student of Rutherford 's, developed a new model of the atom. He proposed that electrons are arranged in concentric circular orbits around the nucleus. This model is patterned on the solar system and is known as the planetary model.
A copper coin is heated and placed in a foam-cup calorimeter containing 32.0 mL of water at 22.0°C. The water reaches a maximum temperature of 24.0°C. How many joules of heat are released by the coin?
The joules of heat released by the copper coin will be the same as the ones absorbed by the water.
To find the heat absorbed by the water can be found using the following formula:
[tex]Q=mCp(T2-T1)[/tex]Where Q is the heat absorbed or released, m is the mass, Cp is the specific heat of the substance and T2 and T1 are the final and initial temperatures of the substance.
m can be found using the given volume of water and its density (1g/mL), Cp is 4.18J/g°C and T2 and T1 are given:
[tex]m=32.0mL\cdot\frac{1g}{mL}=32.0g[/tex][tex]\begin{gathered} Q=32.0g\cdot\frac{4.18J}{g\degree C}\cdot(24.0\degree C-22.0\degree C) \\ Q=267.52J \end{gathered}[/tex]It means that the copper coin released 267.52 joules.
PLEASE ANSWER ASP I ONLY HAVE A FEW MINUTES A student wants to determine the effect of mass on kinetic energy. She will drop two balls of the same size into a pool of
water. Which investigation method should the student use? (1 point)
O She should drop two balls of the same mass from different heights.
O She should drop two balls of the same mass from the same height.
O She should drop two balls with different masses from the same height.
She should drop two balls with different masses from different heights.
Ite
Ite
Answer:
The answer is C) She should drop two balls with different masses from the same height.
Explanation:
Since they want to test the effect of MASS on kinetic energy, they should have different masses but have them both fall from the same height in order to see the difference the mass makes.
A student should drop two balls with different masses from the same height to determine the effect of mass on kinetic energy. Therefore, option (C) is correct.
What is the kinetic energy and potential energy?Kinetic energy (KE) can be described as the energy possessed by a moving body due to its motion. Work will be done when there is a change in the kinetic energy of an object. The kinetic energy is represented as K.E. = ½mv² where ‘m’ is the mass and ‘v’ is the velocity of the object.
Potential Energy (P.E.) can be defined as the energy stored by an object due to the position of the object and can be written in the form of an equation as P.E. = mgh where ‘m’ is the mass, ‘h’ is the height in meters and ‘g’ is the acceleration due to gravity.
The kinetic energy of an object depends upon its mass of the object. Therefore, to understand the effect of mass on kinetic energy, drop two balls with different masses from the same height.
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Consider the thermochemical equation given
below:
CH4 (g) + 2 O2(g) → CO₂ (g) + 2 H₂O(g) ΔΗ = -802 kJ
What is the enthalpy change (AH) if 65.8 grams of O₂ is allowed to react with excess CH4 ?
-1648.11 kJ is the enthalpy change (ΔH) if 65.8 grams of O₂ is allowed to react with excess CH₄.
What is Chemical Reaction ?Chemical reaction is a type of reaction in which one or more substances means reactants are converted to one or more different substances means products are formed.
The given reaction is
CH₄ (g) + 2O₂(g) → CO₂ (g) + 2H₂O(g) ΔΗ = -802 kJ
How to find the number of moles ?We find the number of moles by using this formula
Number of moles = Given Mass/Molar Mass
Here,
Given mass of oxygen = 65.8 g
Molar mass of oxygen = 16 g/mol
Now,
Number of moles = Given Mass/Molar Mass
= 65.8/16
= 4.11 moles
2 moles of O₂ releases 802 kJ of energy.
So, 4.11 moles of O₂ releases = [tex]\frac{802}{2} \times 4.11[/tex]
= 1648.11 kJ
Hence enthalpy change (ΔH) = -1648.11 kJ
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How many joules are required to increase the temperature of 30.0 g of water from 10⁰ C to 100⁰ C vapors.
Answer
11302.2 joules
Explanation
Given:
Mass of water = 30.0 g
Initial temperature, T₁ = 10⁰ C
Final temperature, T₂ = 100⁰ C
Increase in temperature, ΔT = T₂ - T₁ = 100⁰ C - 10⁰ C = 90⁰ C
What to find:
The energy in joules required to increase the temperature of the water.
Step-by-step solution:
The joules required to increase the temperature of the water can be calculated using the formula:
q = mcΔT
Where q is the joules of energy required.
m is the mass of water = 30.0 g
c is the specific heat of water = 4.186 J/g ⁰C
ΔT is the temperature rise = 90 ⁰C
∴ q = 30.0 g x 4.186 J/g ⁰C x 90 ⁰C
q = 11302.2 joules
Hence, 11302.2 joules are required to increase the temperature of 30.0 g of water from 10⁰ C to 100⁰ C vapors.
For the chemical reaction shown,2H,0,(1) + N, H.(I) 4H,O(g) + N, (8)determine how many grams of Nare produced from the reaction of 8.82 g of H2O2 and 6,81 g of N2H4.N2 produced:8TOOLSx10'
In this question, we have the following reaction:
2 H2O2 + N2H4 -> 4 H2O + N2
The reaction is already balanced, the molar ratios are:
2 H2O2 = 1 N2H4
2 H2O2 = 1 N2
1 N2H4 = 1 N2
We have the following mass given in the question and the molar mass:
8.82 grams of H2O2, molar mass = 34.01g/mol
6.81 grams of N2H4, molar mass = 32.04g/mol
N2 molar mass = 28.02g/mol
Now we need to find the limiting reactant, we will start by the H2O2
34.01g = 1 mol
8.82g = x moles
x = 0.26 moles of H2O2 in 8.82 grams
According to the molar ratio, we will need the number of moles of H2O2 divided by 2 in order to find the number of moles of N2H4
0.26/2 = 0.13 moles of N2H4
Now we need to check if we have 0.13 moles of N2H4 or we have more of it:
32.04g = 1 mol
6.81g = x moles
x = 0.212 moles of N2H4, but we only need 0.13 moles, therefore we have an excess of N2H4 and H2O2 is the limiting reactant
Now we need to find the final mass of N2, we will do that by using the number of moles of the limiting reactant, H2O2 0.26 moles, and according to the molar ratio between H2O2 and N2, we need 0.13 moles of N2 being produced, using this number of moles and its molar mass, we can find the final mass:
28.01g = 1 mol
x grams = 0.13 moles
x = 3.64 grams of N2 is produced
Answer = 3.64 grams of N2
6.0 x 10^4 ÷ 4.0 x 10^8
Scientific notation
As per scientific notation rules,scientific notation of 6.0×10^4÷4.0×10^8 value is 1.5×10[tex]^-4[/tex].
What is scientific notation?Scientific notation is defined as a way of expressing numbers which are too large or too small so that they can be easily written in decimal form. It can be referred to the scientific form or the scientific index form or even the standard form.
Base ten notation is used by scientists, engineers as it helps in simplification of arithmetic operations. It contains the significant figures which include all non-zero numbers , the zeroes between significant digits and zeroes which are needed to be significant.
In scientific notation, the base should always be ten. The exponent should be a non-zero integer and it can be either positive or negative.
For example , in the given problem 6.0×10^4=60,000 and 4.0×10^8=40,00,00,000
∴60,000÷40,00,00,000=0.00015 which in scientific notation is expressed as 1.5×10[tex]^-4[/tex]
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Write a balanced chemical equation, including state symbols, for the reaction between
zinc metal and sulfuric acid.
A balanced chemical equation [tex]Zn (s) Zinc + H_{2} SO _{4 }\ (aq) Sulfuric acid → ZnSO _{4}\ ( aq) Zincsulfate (aq) + H {_2} (g) Hydrogen.[/tex]
What is zinc?Zinc is a transition metal with atomic number 30 and is shown in the periodic table with the symbol "Zn". Zinc is one of the cheap metals that we use every day. It is part of the elements that humans have expanded over thousands of years.
Zinc (Zn) is a soft metal with a particularly stable electrical structure (fully filled stable configuration). As a result, their metal joints are weak. They have a high oxidizing power up to oxidation state 2.
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What do these two changes have in common?
roasting a marshmallow over a campfire
boiling sugar to make caramel
Select all that apply.
A: Both conserve mass.
B: Both involve chemical bonds breaking.
C: Both are caused by heating.
D: Both result in a different type of molecule than was there
before.
When compounds are heated they undergo physical changes but new molecules created or existing molecules lost. The common things for the given two changes are they both conserve mass and caused by heating.
What are physical changes?Physical changes include, change in state or phase of a substance. For example, boiling a liquid converts the liquid state into gaseous state. Similarly melting, crystallization, solidification etc. are physical changes.
During a physical change, no bond making or breaking occurring as well as no molecules or atoms are created. Similarly existing molecules cannot be lost.
According mass conservation law, during a chemical or physical change mass of a substance remains constant. Thus reactants have the same as total mass of products.
Therefore, the two common things in the two changes are they are caused by heating and both conserve mass. Thus, option A and C are correct.
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The mole fraction of iron(II) bromide, FeBr2, in an aqueous solution is 6.15×10-2. The percent by mass of iron(II) bromide in the solution is what %?
First, let's put the info into symbols:
[tex]\begin{gathered} X_{FeBr_2}=\text{ 6.15*10}^{-2} \\ \end{gathered}[/tex]As the mole fractions have to add up to 1, we can calculate the water mole fraction, substracting:
[tex]X_{H_2O}=\text{ 1-6.15*10}^{-2}=0.9385[/tex]If we make the supposition that we have 1 mole of the solution, we would have the next quantities of each substance:
[tex]6.15*10^{-2}\text{ moles of FeBr}_2\text{ and 0.9385 moles of water. }[/tex]Now, we can convert these moles into mass through the molecular weight of each substance:
[tex]\begin{gathered} M.W\text{ of water: 2*1+16=18 g/mole} \\ M.W.\text{ of iron \lparen II\rparen bromide: 56+80*2=216 g/mole} \\ \\ 6.15*10^{-2}moles\text{ FeBr}_2*\frac{216\text{ g}}{1\text{ mole}}=\text{ 13.284 g FeBr}_2 \\ \\ 0.9385\text{ moles H}_2O\text{ * }\frac{18\text{ g}}{1\text{ mole}}=16.893\text{ g H}_2O \end{gathered}[/tex]Now, we can calculate the mass percentage, because we have the mass of the substrate and the mass of the solution (the addition of water and iron (II) bromide):
[tex]\%\text{ m/m FeBr}_2=\frac{13.284\text{ g}}{13.284g+16.893g}*100=44.020\text{ \% m/m}[/tex]The answer is that the %m/m of iron bromide in the solution is 44.020%
What step comes after the observation stage in the scientific method?
• asking questions about the observation
• interpreting data
• writing a theory
• publishing your results
The step comes after the observation stage in the scientific method
asking questions about the observation.What is scientific method?The scientific method is the process of objectively establishing facts through testing and experimentation. The basic process involves making an observation, formulating a hypothesis, making a prediction, conducting an experiment and finally analysing the results.
7 steps of the scientific methods are
Make an observation. Ask a question. Form a hypothesis or testable explanation. Make a prediction based on a hypothesis. Test prediction. Iterate: Use the results to make new hypotheses or predictions.To learn more about scientific method, refer;
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