CHEM REGENTS 2019

Show a numerical setup for calculating the molarity of the KOH solution.

(0.010)(15)=M(7.5)

The oxidation number of copper changes from

+2-0

Show a numerical setup for calculating the parts per million of the Na ions in the 500.-gram sample of the bottled water.

0.0033/500 x 1000000

Based on the lab data, show a numerical setup to determine the number of moles of O2 produced. Use 32 g/mol as the gram-formula mass of O2

1 mol/32 g = X mol/0.80 g

Given the formula representing a molecule: A chemical name for this compound is

1-pentanamine

Based on the lab data, determine the mass of KCl produced in the reaction.

1.27 g

Which sample of HCl(aq) reacts at the fastest rate with a 1.0-gram sample of iron filings?

10. mL of 3 M HCl(aq) at 25°C

Based on Table N, determine the total time required for an 80.00-gram sample of cobalt-60 to decay until only 10.00 grams of the sample remain unchanged.

15.813 y

Determine the volume of the sample of CO2(g) if the temperature and pressure are changed to 336 K and 152.0 kPa

151 mL

Balance the equation for the decomposition of KClO3, using the smallest whole-number coefficients.

2 2 3

Which electron configuration represents an atom of chlorine in an excited state?

2-7-8

Determine the formula mass of heavy water, D2O.

20 u

Given the balanced equation for the reaction of butane and oxygen:

20. mol

Complete the nuclear equation, in your answer booklet, for the decay of cobalt-60 by writing a notation for the missing product.

28 60 Ni

Convert the temperature of the NaNO3(s) to kelvins

296 K

Determine the pH value of a solution that is ten times less acidic than the HCl(aq) solution.

3

State the number of significant figures used to express the mass of hydrogen carbonate ions in the table above. [0.180]

3

Based on Table G, determine the additional mass of NaNO3(s) that must be dissolved to saturate the solution at 23°C.

4.0 g - 6.0g

What is the amount of heat absorbed when the temperature of 75 grams of water increases from 20.°C to 35°C?

4700 j

A student measures the mass and volume of a sample of aluminum at room temperature, and calculates the density of Al to be 2.85 grams per cubic centimeter. Based on Table S, what is the percent error for the student's calculated density of Al?

5.6%

What is the percent composition by mass of nitrogen in the compound N2H4 (gram-formula mass 32 g/mol)?

88%

Write the empirical formula for this compound.

C2H4O

Which equation represents fermentation?

C6H12O6 → 2CH3CH2OH + 2CO2

Which substance is an Arrhenius base?

Ca(OH)2

Based on Table F, write the formula of the ion in the bottled water table that would form the least soluble compound when combined with the sulfate ion.

Ca2+

What is the general formula for the homologous series that includes ethene?

CnH2n

Which compound has intermolecular forces?

HF

Compare the radius of a Mg2+ ion to the radius of a Mg atom.

Mg2+ ion has a smaller radius

Which statement explains why NaBr is classified as a compound?

Na and Br are chemically combined in a fixed proportion.

Based on Table I, which compound dissolves in water by an exothermic process?

NaOH

Which ion in the ground state has the same electron configuration as an atom of neon in the ground state?

O2-

Which statement describes the concentration of the two gases in this system?

The concentration of N2O4(g) and the concentration of NO2(g) must be constant.

Using equal masses of reactants, which statement describes the relative amounts of energy released during a chemical reaction and a nuclear reaction?

The nuclear reaction releases more energy than the chemical reaction.

Which statement describes the components of a mixture?

The proportions of components can vary.

Which statement describes the particles of an ideal gas, based on the kinetic molecular theory?

Which statement describes the particles of an ideal gas, based on the kinetic molecular theory?

The effect of a catalyst on a chemical reaction is to provide a new reaction pathway that results in a different

activation energy

Given the formula of a compound: This compound is classified as an

alkyne

As the elements in Period 2 of the Periodic Table are considered in order from left to right, which property generally decreases?

atomic radius

Based on Table N, identify the decay mode of tritium.

beta

State what happens to the boiling point and freezing point of the solution when the solution is diluted with an additional 100. grams of H2O(l).

boiling point:decreases freezing point:increases

Equilibrium can be reached by

both physical changes and chemical changes

Identify the element in ethyl ethanoate that makes it an organic compound

carbon

The atoms of which element bond to one another in chains, rings, and networks?

carbon

During all chemical reactions, charge, mass and energy are

conserved

The ratio of the mass of U-238 to the mass of Pb-206 can be used to

date geological formations

Graphite and diamond are two forms of solid carbon at STP. These forms have

different, different

The degree of polarity of a covalent bond between two atoms is determined by calculating the difference in their

electronegativities

As the first five elements in Group 14 are considered in order from top to bottom, there are changes in both the

electronegativity values and atomic radii

Which two terms represent types of chemical formulas?

empirical and structural

Explain, in terms of subatomic particles, why atoms of H-1, H-2, and H-3 are each electrically neutral.

equal number of protons and electrons

Write the name of the class of organic compounds to which this compound belongs.

esters

Compared to the energy of an electron in the second shell of an atom of sulfur, the energy of an electron in the

first shell is lower

In the ground state, an atom of which element has seven valence electrons?

fluorine

During which two processes does a substance release energy?

freezing and condensation

State, in terms of both the frequency and force of collisions, what would result from decreasing the temperature of the original sample of CO2(g), at constant volume.

frequency and force of collisions decreases

In which type of nuclear reaction do two light nuclei combine to produce a heavier nucleus?

fusion

When an F atom becomes an F ion, the F atom

gains an electron

Compare the penetrating power of the beta and gamma emissions.

gamma emissions have more penetrating power

Which value is defined as the difference between the potential energy of the products and the potential energy of the reactants during a chemical change?

heat of reaction

Which change will cause the equilibrium to shift to the right?

increasing the temperature

The mass of an electron is

less than the mass of a neutron

Chemical systems in nature tend to undergo changes toward

lower energy and higher entropy

Which substance can not be broken down by a chemical change?

magnesium

Compare the mass of the original 200.-milliliter sample of CO2(g) to the mass of the CO2(g) sample when the cylinder is adjusted to a volume of 100. milliliters.

mass remains constant

Which particle remains undeflected when passing through this electric field?

neutron

At STP, which property of a molecular substance is determined by the arrangement of its molecules?

physical state

Write a chemical name for the compound that decomposed.

potassium chlorate

Which particles are found in the nucleus of an argon atom?

protons and neutrons

Explain, in terms of both protons and neutrons, why Co-59 and Co-60 are isotopes of cobalt.

same protons different neutrons

State a change in temperature and a change in pressure of the CO2(g) that would cause it to behave more like an ideal gas.

temp: increase pressure:decrease

Explain, in terms of aqueous ions, why 15.0 mL of a 1.0 M HCl(aq) solution is a better conductor of electricity than 15.0 mL of a 0.010 M HCl(aq) solution.

the 0.010 M solution has fewer mobile ions

Which information is sufficient to differentiate a sample of sodium from a sample of silver?

the reactivity of each sample with water

Magnesium and calcium have similar chemical properties because their atoms in the ground state have

two electrons in the outermost shell

Table sugar can be separated from a mixture of table sugar and sand at STP by adding

water, stirring, and filtering