Chemical Change. Chemical changes occur when bonds are broken and/or formed between molecules or atoms. This means that one substance with a certain set of properties (such as melting point, color, taste, etc) is turned into a different substance with different properties
Answer: Chemical Change.
Explanation: Chemical changes occur when bonds are broken and/or formed between molecules or atoms. This means that one substance with a certain set of properties (such as melting point, color, taste, etc) is turned into a different substance with different properties
true or false...
electromagnetic waves can travel in empty space or space that has no particles
It is true that electromagnetic waves can travel in empty space or space that has no particles.
The correct option is True.
What are electromagnetic waves?Waves of the electromagnetic field make up electromagnetic radiation; they travel through space while carrying momentum and radiant energy. It consists of X-rays, gamma rays, microwaves, infrared, light, and radio waves.
Electromagnetic waves include radio waves, television waves, and microwaves. The only thing separating them is the wavelength. The wavelength is the distance between each wave's peak and the next.
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a typical human’s power rating for an entire day is 100 watts. how much total energy (work), in joules, does a typical human burn in a day?
In a typical day humans consume 8,360,000 J (2000kcal)in a day. Free energy is released as spontaneous reactions take place.
The enthalpy change and the entropy change are mathematically combined to provide the free energy change of a reaction. For a process to be spontaneous, free energy must constantly change in a negative direction. In order for the reaction to proceed in the forward reaction and toward equilibrium, Q also needs to be lower than K. At low temperatures, the reaction will be spontaneous if -T-S is positive and -H is negative (decreasing the magnitude of the entropy term).
According to the preceding calculation, the contained energy of a 70 kilogram human might be estimated as follows:
If you're working in miles rather than kilometers, 70 kilograms times 299,337 kilometers per second squared equals 89,602,639,569
According to this calculation, a 70 kg person would consist of the following:
89,603, MegaJoules or 89,602,639,569 Joules
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what do scientists call the use of leaf shape to understand past climates?
Leaf physiognomy is what scientists call the use of leaf shapes in order to understand the past climates.
Paleoclimate or the past climate can be basically determined by using the proxy data which is basically the data which can be preserved things such as coral, ice cores, pollen, and leaves. Study of paleoclimate is very important to understand how past plants were able to react to the climate change so we that we are able to know how plants will show response to modern human-driven climate change.
Leaf physiognomy is used in the climate-models in order to reconstruct paleotemperature from the fossilized leaves. This study basically supports the idea that changes in the size of the leaves correlates with the temperature change. However, the response that are seen are varied by species and this should be particularly taken into account for the climate-models using leaf physiognomy to infer the paleoclimate.
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You have 10 mL of a 2 M stock solution of NaCl. What volume of NaCl stock would you have to use to make 500 µL of 100 mM NaCI? (NOTE: This is a challenging question!)Match the values to the variables.This is what I solve for 1. Ci500 μL 2. Cf10 mL 3. Vi100 mM 4. Vf2 M 5. None of these
You would need to use 2.5 µL of the 2 M NaCl stock solution to make 500 µL of 100 mM NaCl solution
To make 500 µL of 100 mM NaCl solution, you need to have 5 x 10^-7 moles of NaCl. Given the concentration of your stock solution, the number of moles of NaCl in 10 mL of the solution can be calculated as follows: you would need to use 2.5 µL of the 2 M NaCl stock solution to make 500 µL of 100 mM NaCl solution
moles of NaCl = [tex](2 M) x (10 mL) = 20 x 10^-3[/tex] moles
To obtain [tex]5 x 10^-7[/tex] moles of NaCl, you need to take [tex](5 x 10^-7 moles) / (20 x 10^-3 moles) x (10 mL) = 2.5 x 10^-6 mL = 2.5 µL[/tex] of the stock solution.
Therefore, you would need to use 2.5 µL of the 2 M NaCl stock solution to make 500 µL of 100 mM NaCl solution.
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which of the following is not considered a safety hazard in the laboratory? carrying out a reaction in the fume hood because the reaction generates flammable or toxic gases. storing your backpack on the floor next to your lab bench. disposing of excess acid in the organic waste carboy. pointing the open end of a test tube or flask at yourself or your neighbor. eating or drinking in the laboratory.
Eating or drinking in the laboratory is not considered a safety hazard in the laboratory.
It is important to take safety precautions while working in a laboratory and to always follow the safety protocols in place.
It is important to be aware of the potential hazards in any laboratory environment. Always wear protective clothing such as lab coats, safety glasses, and protective gloves when working with hazardous chemicals or materials. It is also important to be aware of the safety protocols in place for specific experiments, and to follow the instructions provided.
Additionally, it is important to be aware of the potential risks associated with using and storing flammable chemicals, as well as the potential risks associated with using open flames or working with hazardous biological agents. Finally, it is important to ensure that all waste products are handled and disposed of safely.
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Which is one characteristic of some pure substances?
They contain different types of molecules.
They can be homogeneous or heterogeneous.
Only elements are pure substances.
They cannot be changed into simpler substances.
Answer:
Only elements are pure substances.
Answer: c
Explanation:
A solution is made up of 20 mL of water, 35 mL of isopropyl alcohol, and 8 mg of an organic solid. Which of these considered a solute?
a. Water
b. Isopropyl alcohol
c. Medication
d. Water and isopropyl alcohol e. There is no solute in this solution
It is medication. We also understand that there can be only one solvent and numerous solutes.
Water serves as both the solute and the solvent. Using your own expertise, provide an example of each sort of solution. Since both the alcohol and the water are liquid in the provided solution and the alcohol is present in a greater quantity than the water, the alcohol acts as the solvent and the water as the solute. 350 mL of isopropyl alcohol is equal to 70 x 0.05. v% = volume of solute/volume of solution/100. So, going back to our rubbing alcohol, 70 percent (vv) indicates that there are 70 milliliters of the solute, isopropanol, in every 100 milliliters of the solution.
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Why are scientific models important in the study of science?
Answer:
B. that is the answerrrrrrrrrrrrr
Explanation:
i
The following reaction takes place in a 1.00 liter container at 750.0 °C.
H2(g) + CO2(g) ⇌ H2O(g) + CO(g)
At equilibrium there are 0.106 moles of H2, 0.106 moles of CO2, 0.094 moles of water and 0.094 moles of CO. What is the Keq for this reaction?
Answer:
The equilibrium constant (Keq) for a reaction is a measure of the relative concentrations of the products and reactants at equilibrium. The equation for the equilibrium constant (Keq) is:
Keq = [H2O(g)][CO(g)] / [H2(g)][CO2(g)]
In order to find the Keq, we need to substitute the equilibrium concentrations of the species into the equation.
At equilibrium, there are 0.106 moles of H2, 0.106 moles of CO2, 0.094 moles of water and 0.094 moles of CO.
Keq = [0.094 moles H2O][0.094 moles CO] / [0.106 moles H2][0.106 moles CO2]
By canceling out the moles unit and substituting the number we got the value of Keq as:
Keq = 0.0940.094 / 0.1060.106
Keq = 0.87
Therefore, the Keq for this reaction is 0.87.
It is worth to note that the temperature, pressure and volume don't affect the Keq value but they affect the position of equilibrium.
What information should always be recorded when using a balance? The scale What should be done to the weighing container before adding any chemicals? tare the weighing paper or container What will cause the mass displayed on a digital scale to fluctuate? Select What must be done before leaving the balance area
Before using a balance, we should always check and record the scale of the balance before using it and before we add any chemical, we should always tare the weighing paper or the container we are using.
In the laboratory, the measurement of mass is performed by using balances. There are a different types of balance but most of the weighing balances that are in use now are the electronic balances.
There are a few precautions that we need to take care of while using a weighing balance. We should always check the weigh level. We should also always check and record the scale. Before we add any chemicals, we should tare the weight of the paper or the container. We should not use hot chemicals on the scale.
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How much ice (in gram) would have to melt to aborb 331 kJ of energy? The enthalpy of fuion for ice at 0 ∘C i 6. 02 kJ/mol
calculate the change in internal energy, , when 1.34 moles of a diatomic ideal gas is heated from an initial temperature of 156 ºc to a final temperature of 421 ºc.
The change in internal energy, when 1.34 moles of a diatomic ideal gas is heated from an initial temperature of 156 ºc to a final temperature of 421 ºc is 73.8*J
Given:
Number of moles of diatomic gas = 1
Initial temperature = 156 ºc
Final temperature = 421 ºc
Now, change in temperature(T) = 421 ºc-156 ºc = 265 ºc
therefore, change in internal energy = 5/2.nRT
Here, n is the number of diatomic ideal gas heated with value 1.34
R is the universal gas constant with value of 8.314
T is the change in temperature with value 265 ºc
U = 5/2.nRT
U = 5/2*1.34*8.314*265
U = 73.8*J
Internal energy U of a system or a body with well defined boundaries is the total of the kinetic energy due to the motion of molecules and the potential energy associated with the vibrational motion aend electric energy of atoms within molecules. Internal energy also includes the energy in all the chemical bonds.
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1.
When 1• 50g of ethanol
was
apparatus 500g of water.
vapour
20°C to 39-5°C
enthalpy of compustion of
combustion
raised the temp forom
the
Calculate
ethanol
the
The heat that has been taken in by the water is 40.2 kJ.
What is the heat of combustion of the water?We know that when we heat the water the water would be turned from liquid to the vapor state . As such we are interested in the heat that would be evolved when this process would be taking place and we can be ale to write that;
H = mcdT
H = heat that have been evolved or absorbed
m = mass of the water
c = Heat capacity of the water
dT = The temperature change of the water.
As such, we have that;
H = 500 * 4.12 * (39.5 - 20)
H = 40.2 kJ
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determine the ph of the solution resulting when 100 cm3 of 0.50 mol dm–3 hcl(aq) is mixed with 200 cm3 of 0.10 mol dm–3 naoh(aq).
Answer:
The pH of the solution resulting from mixing 100 cm3 of 0.50 mol dm–3 HCl(aq) with 200 cm3 of 0.10 mol dm–3 NaOH(aq) is 12.2, calculated using the formula pH = -log[H+], where [H+] is the concentration of hydrogen ions in the solution.
Explanation:
volume displacement is used to determine the volume of an irregularly shaped metal sample. the gradauted cylinder initially contains 23.2 ml of water. after the metal sample is added to the graduated cylinder, the volume is 32.3 ml . what is the volume of the metal sample?
The volume of the metal sample can be determined by subtracting the initial volume of water (23.2 mL) from the final volume of water and metal (32.3 mL), giving a volume of 9.1 mL for the metal sample.
The volume of a substance can be determined by several methods, including measuring the displacement of a liquid, measuring the displacement of a gas, and using a pycnometer or other volumetric instrument. The most commonly used method for determining the volume of a solid is to measure the displacement of a liquid.
This method involves placing the sample in a graduated cylinder containing a known volume of liquid and measuring the change in volume that occurs when the sample is added. This method can be used to measure the volume of irregularly-shaped objects such as metal samples.
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If you take too much of a chemical when working, what are you supposed to do with the excess?
If we out take too much of a chemical when working, we should not put the excess chemical into the reagent bottle again.
Excess chemicals that are taken out while working should never be returned to the reagent containers. Because by doing so the entire supply might become contaminated. Instead, give your excess chemical to other students or put them in the waste containers.
When too much of chemical from the storage bottle NEVER put the excess chemical back in the bottle. This will contaminate the entire fresh stock. If spillage has occurred, cleaning up the balance is strongly recommended. Do not blow on the balance, clean the balance with a tissue or a small brush.
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given the unbalanced equation co2 h2 ch4 h2o (a) how many moles of water can be produced from 43 moles of carbon dioxide?
86 moles of water can be produced from 43 moles of carbon dioxide.
Given equation is CO2 + H2 -> CH4 + H2O
This equation is unbalanced, a balanced equation would be :-
CO2 + 4 H2 -> CH4 + 2 H2O
According to question, we need to find out the number of moles of water produced by 43 moles of CO2. The stoichiometric ratio of moles of CO2 to moles of H2O is 1:2. This means that 1 mole of CO2 will produce 2 moles of water. Hence, 43 moles of CO2 will produce (2x43) = 86 moles of water. Mole concept is a fundamental concept in stoichiometry. The term "mole" refers to a certain number of molecules: 6.02 x 1023. This is commonly referred to as "Avogadro's number."
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which of the following is not true about molecular orbital theory? the number of molecular orbitals formed is often equal to the number of atomic orbitals that combine to make them. the number of molecular orbitals formed is often equal to the n
The follows statement is not true about molecular orbitals for any substance, the number of electrons in molecular orbitals is equal to the sum of all the valence electrons on the bonding atoms. The correct answer is E.
Because the number of molecular orbitals produced is always equal to the total number of atomic orbitals combined, the claim that the amount of electrons in molecular orbitals equals the sum of all the valence electrons on bonding atoms is untrue.
When electrons are added to orbitals with the same energy, the most stable configuration is predicted by the hund's rule, and a molecule orbital can hold up to two electrons. It is true that low-energy atomic orbitals fill before high-energy atomic orbitals fill.
Your question is incomplete but most probably your full question was which of the following is not true of molecular orbitals?
a) the number of molecular orbitals formed is always equal to the number of atomic orbitals combined.
b) a molecular orbital can accommodate up to two electrons.
c) when electrons are added to orbitals of the same energy, the most stable arrangement is predicted by hund's rule.
d) low-energy molecular orbitals fill before high-energy molecular orbitals fill.
e) for any substance, the number of electrons in molecular orbitals is equal to the sum of all the valence electrons on the bonding atoms.
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if δh for the sublimation of 1 mol of co2(s) is 26.1 kj , calculate δs in j/(k⋅mol) for this phase transition. (hint: use the temperature found in part c to calculate the answer.)
The δs for the sublimation of 1 mol of co2(s) in this phase transition is 87.9 j/(K.mol).
The heat necessary to sublimate (transform from solid to gas) one mole of a substance at a specific combination of temperature and pressure, typically standard temperature and pressure, is known as the enthalpy of sublimation or heat of sublimation in thermodynamics (STP). It is equivalent to the solid's cohesive energy. It is also equal to the typical enthalpy of production of the gaseous metal atoms for elemental metals. Typically, kJ/mol is used to express the heat of sublimation.
From the given data,
δh = 26.1 kj/mol of CO2(s)
δs = ?
for transition phase, Temperature (T) = 298.15 K
then,
δs = δh/T = 26100 j/mol /298.15 K = 87.9 j/(K.mol)
δs = 87.9 j/(K.mol)
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please help asap! last box, i know the functional group name is amide.
The amide group has the amine moiety and the carboxylic moiety.
What is the amide functional group?An amide functional group is a molecule composed of a nitrogen atom bonded to a carbon atom, with the formula -CONH-. It is commonly found in organic compounds such as proteins and synthetic polymers.
We can now see that the chain that came form the carboxyl group is the alky chain of the amide moiety that is in the compound that have been shown in the image attached in the question that have been given above.
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What is combined gas law and ideal gas law?
While the ideal gas law also considers the number of moles, the combined gas law only considers pressure, temperature, and volume.
What exactly does the ideal gas law mean?In conclusion, the Ideal Gas Law asserts that all gases have the same number of molecules when they are at the same temperature, pressure, and volume (but not the same mass). Remember that when the temperature and pressure are close to where a substance will become a liquid or solid, the Ideal Gas rule does not apply.
What is the combined gas law?The three previously established laws, Boyle's law PV = K, Charles's law V/T = K, and Gay-law Lussac's P/T = K, are combined to form the combined gas law. Therefore, PV/T = K, where P is pressure, T is temperature, V is volume, and K is a constant, is the formula for the combined gas law.
What are real-world applications of the ideal gas law?Vehicle airbags operate according to the ideal gas law. The various gases immediately fill up inside the airbags after they are inserted, inflating them. The interaction between sodium azide and potassium nitrate fills the airbags with nitrogen gas.
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the estimated original concentration in a sample is 5.12 x 10^9 cfu/ml. you plan to set up a series of 1:10 dilutions and then plate 0.1 ml on your spread plate. which tube do you need to plate out to yield a countable plate?
You need to plate out tube with sample original concentration is 5.1 × 10⁹ CFU / ml to yield a countable plate.
The starting dosage is5.1 × 10⁹ × 10⁻¹ = 5.1 × 10⁸ CFU/ml
CFU levels must range from 10 to 200 per milliliter in order to produce a countable plate.
Let's make 0.1 ml into 1 ml by dilution.
As a result, the concentration is reduced to5.1 × 10⁹ × 10⁻¹ = 5.1 × 10⁸ CFU/ml
It can be lowered to 5.1 × 10¹to reduce the concentration between 10 and 200.
5.1 × 10¹ CFU/ml is the final concentration.
Initial concentration: 5.1 × 10⁹ CFU/ml
Sample volume is 5.1 × 10¹ CFU = 5.1 × 10¹ CFU × (1 ml / 5.1 × 10⁹ CFU)
= 1.0 × 10⁻⁸ ml
This is the volume must be consumed to obtain 51 CFU of countable value.
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how atoms interact with each other lab activity 8
Atoms interact with each other through various chemical bonds.
Lab activity 8 might involve exploring the different ways that atoms interact with each other, specifically through the formation of chemical bonds. Chemical bonds are interactions between atoms that result in the formation of a new molecule. There are several types of chemical bonds, including covalent bonds, ionic bonds, and metallic bonds.
In a covalent bond, two or more atoms share electrons to form a strong, stable bond. For example, in a water molecule (H2O), two hydrogen atoms share electrons with an oxygen atom.
In an ionic bond, electrons are transferred from one atom to another, resulting in the formation of ions. For example, when sodium (Na) reacts with chlorine (Cl), an electron is transferred from the sodium atom to the chlorine atom, forming a sodium ion (Na+) and a chloride ion (Cl-). The ions are attracted to each other, forming an ionic bond.
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When is the density of water 1 g/mL How can we measure density?
The standard definition of water's density is 1 g/mL at 4 °C.
What is density?A substance's density is determined by how much mass there is per unit volume. It is known as the mass-to-volume ratio, and is commonly given in quantities of grammes per cubic centimetre (g/cm3) or kilogrammes per cubic metre (kg/m3).
How do you determine it?The standard definition of water's density is 1 g/mL at 4 °C. In other words, a millilitre of water weighs exactly one gramme at this temperature. Although temperature and pressure can cause a small variation in water's density, the value of 1 g/mL at 4°C is typically regarded as a standard reference.
There are several ways to measure density, but the most popular one uses a balance to calculate the sample's mass and a graduated cylinder or another tool to calculate its volume. The mass divided by the volume is then used to calculate the density.
A 100 mL graduated cylinder filled with 50 mL of water, for instance, would be weighed with the water inside before being empty to determine the mass of the water. The density would then be determined by dividing the water's mass by its volume (50 mL).
With a balance and graduated cylinder or an oscillating U-tube densitometer, the mass and volume of the sample must be determined in order to quantify the density of the substance.
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2n2o(g) -> 2n2(g) o2(g). b. in the first 15.0 s of the reaction, 0.015 mol of o2 is produced in a reaction vessel with a volume of 0.500 l. what is the average rate of reaction during this time?
The average rate of reaction over the first 15.0 s is 0.001 mol/s.
The average rate of reaction can be calculated as the change in the amount of product (O2) divided by the time interval. In this case, the amount of O2 produced in the first 15.0 s is 0.015 mol. So, the average rate of reaction is given by:
average rate = (0.015 mol) / (15.0 s) = 0.001 mol/s.This value represents the average rate of reaction over the first 15.0 s and can be used to estimate the amount of O2 produced at a different time during the reaction. Note that this is an average rate, and the actual rate of the reaction may vary over the course of the reaction.
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Three students are asked to discuss why the water only condensed on the upper half of the test tube. Which student employs correct scientific reasoning?• Student 1: Water is left to the mouth of the test tube because ourbon dioxide leaves hest and water is then left behind this to the difference on the motor masse • Student 2: The water only goodensed on the upper ball of the test tube because the upper half was cool enough to allow this phase change to occur • Student 3: As the carbon dioxide left the test tube it pushed the water vapor out a. Student 1 b. Student 2c. Student 3
Answer:
hi im new here
Explanation:
choose the response that includes all the items listed below that are pure substances. in. orange juice ii. steam iii. wine iv. oxygen v. vegetable soup
Below which is a pure substance is iv. oxygen
What is a pure substance?A pure substance is a collection of atoms that are chemically the same. Examples are water, oxygen, and iron. Water contains only water atoms. Oxygen contains only oxygen atoms.
Pure substances can be further divided into elements and compounds. Elements are pure substances that cannot be broken down into simpler substances by chemical reactions. They are already in their simplest form.
Compounds are substances that can be broken down into simpler substances through chemical reactions. Compounds are usually a combination of two or more elements. For example water (H2O).
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which of the following is a chemical property of water? group of answer choices salt dissolves in water water has a density of 1000 kg/m3. water reacts violently with magnesium. ice floats in water.
Among the given options, a chemical property of water is that water reacts violently with magnesium.
Chemical properties are properties that describe the behavior and characteristics of a substance in terms of its interactions with other substances. Water's reactivity with magnesium is a chemical property because it describes how water interacts with magnesium at a molecular level.
The other options listed (salt dissolves in water, water has a density of 1000 kg/m3, and ice floats in water) are physical properties.
Physical properties are those properties which can be measured without changing the composition of matter. It describes the physical characteristics of a substance such as its appearance, density, and solubility.
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What is wrong with the lewis structure below? Explain how the correct structure should appear.
Answer:
way too many valence electrons
Explanation:
By putting a double bond on F, you give it 10 valence electrons which breaks the octet rule
write the structure of the major organic products formed in the reaction of ozonide with dimethyl sulfide (ch3)2s.
The following are the primary organic compounds generated by the reaction of ozonide with dimethyl sulphide (CH3)2S: (CH3)2SO dimethyl sulfoxide, and (CH3)2SO2 dimethyl sulfone.
When ozonide reacts with dimethyl sulphide (CH3)2S, two main organic products are formed: methyl sulfoxide (CH3SO) and dimethyl sulfoxide (CH3)2SO.
To generate the end products, the sulphide sulphur atom is nucleophilically added to the ozonide intermediate, followed by the migration of a methyl group and a proton shift.
These organic products' structures can be written as follows:
CH3SO (methyl sulfoxide): CH3-S-O
CH3-S(=O) dimethyl sulfoxide (CH3)2SO-CH3
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