Answer:
Identify a process that is NOT reversible.
Melting of snow
baking of bread
deposition of carbon dioxide
freezing water
melting of aluminum
Explanation:
A physical change is the one in which there is a change only in its physical state, color, the appearance of the substance. But the chemical composition of the substance remains unchanged.
It is a temporary change and can be reversed easily.
For example:
melting, freezing, deposition etc.
Baking is a permanent change and the chemical composition of the substance changes.
Hence, among the given options, baking of bread is not a reversible change.
Out of the following all are physical changes except baking of bread and physical changes are reversible so the process which is not reversible is baking of bread.
What are physical changes?Physical changes are defined as changes which affect only the form of a substance but not it's chemical composition. They are used to separate mixtures in to chemical components but cannot be used to separate compounds to simpler compounds.
Physical changes are always reversible using physical means and involve a change in the physical properties.Examples of physical changes include melting,boiling , change in texture, size,color,volume and density.Magnetism, crystallization, formation of alloys are all reversible and hence physical changes.
They involve only rearrangement of atoms and are often characterized to be changes which are reversible.
Learn more about physical changes,here:
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A scientist is conducting a Sanger's sequencing experiment to determine the number of polypeptides present in an oligomeric protein. The molecular weight of the protein is 18000 g/mol . After the reaction of 520 mg of the protein with 1‑fluoro‑2,4‑dinitrobenzene, the peptide bonds were hydrolyzed with an acid. As a result, the scientist obtained 39 mg of 2,4‑dinitrophenyl serine. What is the number of the polypeptide chains present in the oligomer?
Answer:
Depends on molecule.
Explanation:
The number of the polypeptide chains present in the oligomer depends on the molecule. Some molecules have more polypeptide chains whereas some of them have less polypeptide chains. For example, Hemoglobin is a oligomer that consists of four Polypeptide Chains, two of these Polypeptide Chains are α-globin molecules, each comprise of 141 amino acids, and the other two are (β, γ, δ, or ε) globins, each consist of 146 amino acids.
A 0.50 mol sample of COBr2 is transferred to a 9.50-L flask and heated until equilibrium is attained. Calculate the equilibrium concentrations of each species.
Answer:
Equlibrium concentration for each species ae as follows:
[CO] = 0.043 mol/L
[Br₂] = 0.043 mol/L
[COBr₂] = 0.01 mol/L
Explanation:
Let take a look at the chemical equation taking place at equilibrium
COBr2(g) ⇄ CO(g) + Br2(g)
The concentration of COBr2 i.e.
[COBr2] = no of moles/volume
= 0.50 mol/9.50 L
[COBr2] = 0.0530 mol/L
At standard conditions
Kc for COBr2 = 0.190
Now, the ICE table for the above reaction can be computed as follows:
COBr2(g) ⇄ CO(g) + Br2(g)
Initial 0.053 0 0
Change -x +x +x
Equilibrium (0.053 - x) x x
[tex]\mathsf{K_c = \dfrac{[CO][Br_2]}{[COBr_2]}}[/tex]
[tex]K_c = \dfrac{(x) (x)}{(0,053 -x)}[/tex]
[tex]0.190= \dfrac{x^2}{(0.053 -x)}[/tex]
x² = 0.190(0.053 - x)
x² = 0.01007 - 0.190x
x² + 0.190x - 0.01007 = 0
Using quadratic formula:
x ≅ 0.043 mol/L
SInce: x = [CO][Br₂] = 0.043 mol/L
[COBr₂] = 0.053 - x
[COBr₂] = 0.053 - 0.043 mol/L
[COBr₂] = 0.01 mol/L
Write the balanced half-equations for silver + oxygen= silver oxide:
Answer: The balanced half-equations for silver + oxygen= silver oxide are:
Oxidation-half reaction: [tex]Ag \rightarrow 2Ag^{+} + 2e^{-}[/tex]
Reduction-half reaction: [tex]O_{2} + 2e^{-} \rightarrow 2O^{-}[/tex]
Explanation:
The word equation is as follows.
silver + oxygen = silver oxide
In terms of chemical formulas this equation can be written as follows.
[tex]Ag + O_{2} \rightarrow Ag_{2}O[/tex]
The removal on electron(s) from an atom, ion or molecule in a chemical reaction is called oxidation.
The gain of electron(s) by an atom, ion or molecule in a chemical reaction is called reduction.
Hence, half-reaction equations for the given reaction is as follows.
Oxidation-half reaction: [tex]Ag \rightarrow 2Ag^{+} + 2e^{-}[/tex]
Reduction-half reaction: [tex]O_{2} + 2e^{-} \rightarrow 2O^{-}[/tex]
As the number of atoms participating in the reaction are equal. Hence, the half-equations are balanced.
Thus, we can conclude that the balanced half-equations for silver + oxygen = silver oxide are:
Oxidation-half reaction: [tex]Ag \rightarrow 2Ag^{+} + 2e^{-}[/tex]
Reduction-half reaction: [tex]O_{2} + 2e^{-} \rightarrow 2O^{-}[/tex]
Which of the following is an alkaline earth metal?
A Carbon
B aluminum
C magnesium
D silicon
Answer:
Magnesium.
Explanation:
Because it is in group II
Ammonia and oxygen react to form nitrogen monoxide and water. Construct your own balanced equation to determine the amount of NO and H2O that would form when 2.78 mol NH3 and 5.19 mol O2 react.
Answer:
The amount of NO formed s 2.78 moles or 83.4 grams
The amount of H2O formed is 4.17 moles or 75.1 grams
Explanation:
Step 1: Data given
Ammonia = NH3
Oxygen = O2
nitrogen monoxide = NO
water = H2O
Number of moles NH3 = 2.78 moles
Number of O2 = 5.19 moles
Step 2: The balanced reaction
4NH3 + 5O2 → 4NO + 6H2O
Step 3: Calculate moles of products
For 4 moles NH3 we need 5 moles O2 to produce 4 moles NO and 6 moles H2O
NH3 is the limiting reactant
All the NH3 will react. There will be 0 moles of NH3 left
For 4 moles NH3 we need 5 moles O2
For 2.78 moles NH3 we need 5/4 * 2.78 = 3.475 moles
There will be left 5.19 - 3.475 = 1.715 moles O2
For 4 moles NH3 we need 5 moles O2 to produce 4 moles NO and 6 moles H2O
For 2.78 moles NH3 we'll have 2.78 moles NO and 6/4 * 2.78 = 4.17 moles H2O
Step 4: Calculate mass of NO and H2O
Mass = moles * molar mass
Mass NO = 2.78 moles * 30.01 g/mol
Mass NO = 83.43 grams
Mass H2O = 4.17 moles * 18.02 g/mol
Mass H2O = 75.14 grams
The amount of NO formed s 2.78 moles or 83.4 grams
The amount of H2O formed is 4.17 moles or 75.1 grams
Classify each of the following as a strong acid or a weak acid and indicate how each should be written in aqueous solution. Classify ... In solution this acid should be written as: weak 1. hydrocyanic acid H3O CN- _______ 2. hydrobromic acid
Answer:
HCN, weak acid
H⁺, Br⁻, strong acid
Explanation:
Hydrocyanic acid is a weak acid, according to the following equation.
HCN(aq) ⇄ H⁺(aq) + CN⁻(aq)
Thus, it should be written in the undissociated form (HCN).
Hydrobromic acid is a strong acid, according to the following equation.
HBr(aq) ⇒ H⁺(aq) + Br⁻(aq)
Thus, it should be written in the ionic form (H⁺, Br⁻).
define saturated and unsaturated fats
Explanation:
Saturated fats are defined as the fat where fatty acid chains contain only single bonds.
For example, stearic acid, palmitic acid etc.
Unsaturated fats are defined as the fat where fatty acids contain one or more number of double bonds on the carbon atoms.
For example, oleic acid, palmitoleic acid etc.
There is a type of algae that lives in the cells of corals. These algae process carbon through photosynthesis and pass it on to corals in the form of glucose, a sugar that provides the energy corals need to survive and function. Corals offer protection for the algae and also produce wastes that the algae need for photosynthesis.
Warmer water temperatures caused by global warming disrupt photosynthesis in the algae, causing a poisonous build-up that threatens corals. This causes corals to force the algae out of their cells.
Answer:
Explanation:
Sample Response: If global warming continues, corals will continue to expel the algae from their cells to avoid poisonous buildup. This will cause corals to die. Without corals, the algae are not protected and cannot perform photosynthesis. This will cause the algae to die as well.
43.0 mL of 1.49 M perchloric acid is added to 14.0 mL of calcium hydroxide, and the resulting solution is found to be acidic.
29.1 mL of 0.498 M barium hydroxide is required to reach neutrality.
What is the molarity of the original calcium hydroxide solution?
Answer:
2.29 M
Explanation:
Equation of the reaction;
Ca(OH)2(aq) + 2HClO4(aq) → 2H2O(l) + Ca(ClO4)2(aq)
Concentration of acid CA = 1.49 M
Concentration of base CB= ????
Volume of acid VA= 43.0 ml
Volume of base VB= 14.0 ml
Number of moles of acid NA = 2 moles
Number of moles of base NB = 1 mole
CAVA/CBVB = NA/NB
CAVANB =CBVBNA
CB= CAVANB/VBNA
CB= 1.49 × 43.0 × 1/14.0 × 2
CB= 2.29 M
if a=1/2(a+b)h,express a in terms of A,b and h. pls solve with step by step
Answer:
[tex] a = \frac {2A - bh}{h} [/tex]
Explanation:
Given the following mathematical expression;
A = ½(a + b)h
To make a the subject of formula (express a in terms of A, b and h);
First of all, we would cross-multiply;
2A = (a + b)h
Opening the bracket, we have;
2A = ah + bh
Rearranging the mathematical expression, we have;
ah = 2A - bh
[tex] a = \frac {2A - bh}{h} [/tex]
Which substance has nonpolar covalent bonds?
CO
NO2
H2
NaBr
Answer:
H2
Explanation:
Answer:
[tex]{ \bf{H _{2} }} \\ { \tt{hydrogen \: gas}}[/tex]
The speed of light_____ meters per second
☛ 299,792,458 meters per second.
༒How much does the earth weigh?☆☆☆☆☆☆☆☆☆☆☆☆
Answer:
Earth has a mass of 5.9736×1024 kg
5.972×10²⁴kghope it is helpful to you
the question is in the attachment
Answer:
About redox reaction which of the given statements are true?
Explanation:
Redox reaction is the one in which both oxidation and reduction reactions take place simultaneously.
For example:
[tex]C(s)+O_2(g)->CO_2(g)[/tex]
In this reaction, carbon undergoes oxidation and oxygen undergoes reduction simultaneously.
During this reaction, mutual exchange of electrosn take place between the oxidant and the reductant.
Among the given options,
Option B. electrons are transferred
and
option C.They include both oxidation and reduction takes place are the correct answers.
Complete and balance the equations for the given single displacement reactions. Write the reaction in molecular form. Phases are optional. If you need to clear your work and reset the equation, click the CLR button.Li(s) + H2O---------- Ca(s) + H2O ---------------
Answer:
Li(s) + H2O(l) -----> LiOH(aq) + H2(g)
Ca(s) + 2H2O(l) ---------------> Ca(OH)2(aq) + H2(g)
Explanation:
Metals react with water to yield the metal hydroxide and hydrogen gas as shown in the answer above.
The reaction equations were balanced, the number of atoms of each element on both side of the reaction equation is exactly the same.
This is the way to write a balanced reaction equation for the species shown in the question.
Determine the kinds of intermolecular forces that are present in each element or compound. Part A KrKr Check all that apply. Check all that apply. dispersion forces dipole-dipole forces hydrogen bonding
Answer:
The kinds of intermolecular forces that are present in each element Kr-Kr.
Explanation:
Since Kr is an inert gas and in atomic form only it is highly stable.
So, Kr gas does not form molecules.
Between the atoms of inert gas, there exist London dispersion forces.
Hence, the intermolecular forces that are present between Kr-Kr atoms is London dispersion forces.
According to the following pKa values listed for a set of acids, which would lead to the strongest conjugate base?
a. -2.
b. 1.
c. 7.
d. 25.
e. 50.
In a pure metal, the electrons can be thought of as [ Select ] throughout the metal. Using molecular orbital theory, there [ Select ] an energy gap between the filled molecular orbitals and empty molecular orbitals. The [ Select ] orbitals are typically higher in energy and are mostly [ Select ] .
Answer:
Explanation:
In a pure metal, the electrons can be thought of as [concentrated] around atoms throughout the metal. Using molecular orbital theory, there [is ] an energy gap between the filled molecular orbitals and empty molecular orbitals. The [antibonding] orbitals are typically higher in energy and are mostly (filled]
determine the number of atoms of H in 35.0 grams of C2H4O2
Answer:
1.40x10^24 atoms of H
Explanation:
Na2CO3 reacts with dil.HCl to produce NaCl, H2O and CO2. If 21.2 g of pure Na2CO3 are added in a solution containing 21.9g HCl , a. Find the limiting reagent. (2) b. Calculate the number of moles of excess reagent left over.(2) c. Calculate the number of molecules of H2O formed.(1) d. Calculate volume of CO2 gas produced at 270C and 760mm Hg pressure.(2) e. Write significance of limiting reagent
Answer:
See explanation
Explanation:
Equation of the reaction;
Na2CO3(aq) + 2HCl(aq) -------> 2NaCl(aq) + H2O(l) + CO2(g)
Number of moles of Na2CO3 = 21.2g/106g/mol = 0.2 moles Na2CO3
Number of moles of HCl = 21.9g/36.5g/mol = 0.6 moles of HCl
1 mole of Na2CO3 reacts with 2 moles of HCl
0.2 moles of Na2CO3 reacts with 0.2 × 2/1 = 0.4 moles of HCl
Hence Na2CO3 is the limiting reactant
Since there is 0.6 moles of HCl present, the number of moles of excess reagent=
0.6 moles - 0.4 moles = 0.2 moles of HCl
1 mole of Na2CO3 forms 1 mole of water
0.2 moles of Na2CO3 forms 0.2 moles of water
Number of molecules of water formed = 0.2 moles × 6.02 × 10^23 = 1.2 × 10^23 molecules of water
1 mole of Na2CO3 yields 1 mole of CO2
0.2 moles of Na2CO3 yields 0.2 moles of CO2
1 mole of CO2 occupies 22.4 L
0.2 moles of CO2 occupies 0.2 × 22.4 = 4.48 L at STP
Hence;
V1=4.48 L
T1 = 273 K
P1= 760 mmHg
T2 = 27°C + 273 = 300 K
P2 = 760 mmHg
V2 =
P1V1/T1 = P2V2/T2
P1V1T2 = P2V2T1
V2 = P1V1T2/P2T1
V2 = 760 × 4.48 × 300/760 × 273
V2= 4.9 L
The limiting reactant is the reactant that determines the amount of product formed in a reaction. When the limiting reactant is exhausted, the reaction stops.
The length of a covalent bond depends upon the size of the atoms and the bond order.
a. True
b. False
Answer:
True
Explanation:
The length of covalent bond depends upon the size of atoms and the bond order.
13. What would you expect the pH of an aqueous solution of tertiary bromide in water to be (acidic, neutral, or basic)
Answer:
oshfjidgshsjdh
Explanation:
918474828
What effect does hybridization have on chemical bond
Underneath the ocean floor, methane can exist as a solid known as methane hydrate. Methane hydrate forms when large amounts of methane become trapped in the crystal structure of water, which develops into a solid similar to ice. A scientist working for a deep water drilling company is studying the properties of the three different phases of methane: methane hydrate, liquified natural gas, and natural gas. Which of the properties is true
Answer:
Methane is present in solid, liquid and gaseous form.
Explanation:
Methane hydrate is present in solid state when the hydrogen-bonded water and methane gas come into contact at high pressures and low temperatures in the deep oceans while on the other hand, methane which is present inside the earth surface in gaseous form due to non-availability of water that can combine with methane. Methane is also found in liquid form when it is cool with high pressure and low temperature.
? Question
In an ozone molecule, the three atoms must be connected, so there must at least be a single bond between them. Place
dots in pairs around the oxygen atoms until each oxygen atom has eight valence electrons, starting with the atoms on the
outside and doing the central atom last if there are enough. Do not exceed the total number of valence electrons
identified in part A. Remember that the dashes between the oxygen atoms, which represent single bonds, each indicate
the presence of two valence electrons.
A is the answer
In an ozone molecule, the three atoms must be connected, so there must at least be a single bond between them. Place
dots in pairs around the oxygen atoms until each oxygen atom has eight valence electrons, starting with the atoms on the
outside and doing the central atom last if there are enough. Do not exceed the total number of valence electrons
identified in part A. Remember that the dashes between the oxygen atoms, which represent single bonds, each indicate
the presence of two valence electrons
Answer:
Explanation: i did it
Analysis of an unknown substance showed that it has a high boiling point and is brittle. It is an insulator as a solid but conducts electricity when melted. Which of the following substances would have those characteristics?
a. HCl
b. Al
c. SiF4
d. KBr
e. I2
Answer:
The correct option is D (KBr)
Explanation:
Potassium bromide (KBr) is a typical example of an IONIC CRYSTAL. Positive and negative ions are arranged in a regular pattern to give a giant crystal lattice in an ionic solid.
Ionic crystals are hard and have high melting points because the electrostatic forces holding the ions are strong. In the solid state, ionic compounds are poor conductors of electricity because the ions are held rigidly in place and so cannot moves about.
When melted or when dissolved in water, the ions are free to move about and the ionic substances become good conductors of electricity.
Ionic crystals are also BRITTLE. When struck, they tend to shatter because as planes of ions slip by one another, they pass from a condition of mutual attraction to one of mutual repulsion.
What effect would a decrease in volume have on pressure, assuming that temperature (T) and moles of gas (n) are kept constant
Answer:
Pressure increases
Explanation:
Boyle's law states that; '' the volume of a given mass of ideal gas is inversely proportional to its pressure at constant temperature.
Hence, when the volume of a given mass of ideal gas is decreased, the molecules of the gas come closer together so they collide with each other and the walls of the container more frequently.
This implies that the pressure of the gas increases as volume decreases in accordance with Boyle's law.
According to the Arrhenius equation, changing which factors will affect the
rate constant?
A. Temperature and the ideal gas constant
B. The activation energy and the constant A
C. The constant A and the temperature
D. Temperature and activation energy
Answer:
e−(Ea/RT): the fraction of the molecules present in a gas which have energies equal to or in excess of activation energy at a particular temperature
Answer:
D. Temperature and activation energy is the correct answer
Explanation:
^_^
Excited sodium atoms may emit radiation having a wavelength of 589nm. a) What is the wavelength in meters
Answer: When excited sodium atoms may emit radiation having a wavelength of 589nm. It's wavelength in meters is [tex]589 \times 10^{-9} m[/tex].
Explanation:
Given: Wavelength = 589 nm
It is known that,
[tex]1 nm = 10^{-9} m[/tex]
Hence, 589 nm is converted into meters as follows.
[tex]589 nm = 589 nm \times \frac{10^{-9}m}{1 nm}\\= 589 \times 10^{-9} m[/tex]
Thus, we can conclude that when excited sodium atoms may emit radiation having a wavelength of 589nm. It's wavelength in meters is [tex]589 \times 10^{-9} m[/tex].
A compound was analyzed and found to contain 76.57% carbon, 6.43% hydrogen, and 17.00% oxygen by mass. Calculate the empirical formula of the compound. If the molar mass of the compound is 94.11 g/mol, what is the molecular formula of the compound?
A second compound is composed of 53.30% Carbon 11.19% Hydrogen and 35.51% Oxygen by mass.Please Calculate the empirical formula of the compound of the molar mass of the compound is 90.12g/mol, what is the molecular formula for that compound?
Answer:
See explanation
Explanation:
First we divide the percentage by mass of each element by it's relative atomic mass then we divide the quotients obtained by the lowest ratio obtained in the first step.
C- 76.57/12, H= 6.43/1, O = 17.00/16
C- 6.38/1.06, H= 6.43/1.06, O= 1.06/1.06
C- 6, H- 6, O- 1
Empirical formula: C6H6O
[(12 ×6) + (6 × 1) + (16 × 1)]n=94.11
[72 + 6 +16]n = 94.11
n = 94.11/94
n= 1
Molecular formula = C6H6O
2)
C- 53.30/12, H- 11.19/1, O- 35.51/16
C- 4.44/2.22, H- 11.19/2.22, O- 2.22/2.22
C- 2, H- 5, O- 1
Empirical formula: C2H5O
[(2×12) + (5× 1) + (1×16)]n = 90.12
[24 + 5 + 16] n = 90.12
n= 90.12/45
n= 2
Molecular formula = C4H10O2
