QUIZ 1: CHEMICAL CHANGE TO ENTROPY AND GIBBS FREE ENERGY

Determine the value for the following reaction. N2(g) + 3H2(g) → 2NH3(g)+ 22,000 cal ΔH = _____ -22,000 kcal 22,000 kcal 22 kcal -22 kcal

-22 kcal

How many kilojoules are associated with the formation of 2 moles of HBr(g)?

-73

1.a reaction that absorbs energy 2. a reaction that releases heat 3. the amount of heat released or absorbed by a reaction 4.the solid formed as a result of chemicals reacting together from a solution

1. endothermic 2. exothermic 3. enthalpy 4. precipitate

The two balanced equations (1) and (2) are for reactions in which gaseous carbon dioxide is produced from the combustion of (1) solid carbon and (2) gaseous carbon monoxide. 1. C(s) + O2(g) CO2(g) + 94.0 kcal2. CO(g) + ½ O2(g) CO2(g) + 67.6 kcal When 112 grams of carbon monoxide are consumed according to equation 2, which of the following occurs? (atomic weights: C = 12.0 g/mol, O = 16.0 g/mol) 2.00 moles of oxygen are consumed. 0.25 mole of carbon dioxide is produced. 1.0 mole of carbon dioxide is produced. 67.6 kcal of heat are generated. 0.50 mole of oxygen is consumed.

2.00 moles of oxygen are consumed.

The combustion of 14 grams of CO according to the reaction CO(g) + ½O2(g) CO2(g) + 67.6 kcal gives off how much heat? 6,716 kcal 1,514 kcal 34 kcal 135 kcal none of the above

34 kcal

The combustion of 1 mole of CO according to the reaction CO(g) + ½O2(g) CO2(g) + 67.6 kcal gives off how much heat? 67.6 kcal 1,514 kcal 33.3 kcal 135.2 kcal none of the above

67.6 kcal

Which of the following equations represents an exothermic reaction? (Select all that apply.) NH 3(g) + 12.0 kcal ½N 2(g) + 3/2 H 2(g) C (graphite) C (diamond), H = - 0.45 kcal C + 2S CS 2, H = 27,550 cal CH 4 + 2O 2 CO 2 + 2H 2O + 212,800 cal 2H 2O 2H 2 + O 2, H = +58 kcal

C (graphite) C (diamond), H = - 0.45 kcal CH 4 + 2O 2 CO 2 + 2H 2O + 212,800 cal

Determine the value for the following reaction. 2HI(g) + 2.4 kcal → H2(g) + l2(g) ΔH = _____ 0.0024 kcal -2.4 kcal 2.4 kcal -0.0024 kcal

2.4 kcal

Endothermic means to lose energy. True False

False

A negative H means an exothermic reaction. True False

True

When a solid compound is formed from chemicals that are in a solution, it is called a _________

precipitate

Which is more stable, the reactants or products?

reactants

The formation of a precipitate is an indication of a chemical change. True False

True

When a chemical reaction takes place, the number of atoms of each element in the reactants _________________ the number of atoms of each element in the products.

must be equal to

A temperature change in a reaction indicates a physical change. True False

False

All reactions involving a change in temperature are exothermic. True False

False

Changing colors is not an indication of a chemical change. True False

False

Energy can be measured directly with a calorimeter. True False

False

Gas produced from a reaction is a phase change, not a chemical change. True False

False

Two objects with the same temperature must have an equal quantity of heat. True False

False

What happens to the energy release of an exothermic reaction? It raises the temperature of the reactants. It is released to the surroundings. It increases the bond energy of the reactants.

It is released to the surroundings.

What is the common device used for measuring heat transfer for chemical reactions? calorimeter thermometer molameter

calorimeter

Which of the following does not indicate a chemical change? color change crushing a solid into a powder precipitate formation gas evolution

crushing a solid into a powder

If we read the reaction as X + Y → Z + Q it is

endothermic

If we reverse the reaction to read Z + Q → X + Y, the +ΔH would be a -ΔH. Does this indicate that heat is given off or absorbed in the reverse reaction?

given off

When the products of a reaction have more energy than the reactants: the reactants gave up energy the reaction is exothermic the reaction is endothermic the H is positive

the reaction is endothermic the H is positive

The two balanced equations (1) and (2) are for reactions in which gaseous carbon dioxide is produced from the combustion of (1) solid carbon and (2) gaseous carbon monoxide. 1. C(s) + O2(g) CO2(g) + 94.0 kcal2. CO(g) + ½ O2(g) CO2(g) + 67.6 kcal On the basis of the information given in equation (1) and assuming no change in temperature or pressure, one can correctly conclude that the total number of moles of products is the same as the total number of moles of reactants the rate of reaction is rapid the weights of the products are greater than those of the reactants there will be an increase in the volume of the reactants and products taken together as the reaction proceeds the reaction is exothermic

the reaction is exothermic

Which reaction is endothermic? ½ N 2(g) + O 2(g) + 8.1 kcal NO 2(g) H 2(g) + ½ O 2(g) H 2O(g), H = -57.82 kcal ½ N 2(g) + 3/2H 2(g) NH 3(g) + 11.0 kcal C (diamond) + O 2(g) CO 2, H = -94.50 kcal

½ N 2(g) + O 2(g) + 8.1 kcal NO 2(g)