Chem 111 Test Review

Given the three statements below, which answer is correct?

I. A thermochemical equation must include the physical state of all substances.

II. The coefficients in a thermochemical equation are interpreted as moles.

III. The sign of DH is negative for an endothermic reaction.

• I and III are true, II is false

• I, II, and III are all false

• I, II, and III are all true

• I and II are true, III is false

• . II and III are true, I is false

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Given the thermochemical equation: 2 H2O2 (l) -> 2 H2O (l) + O2 (g) delta H = -189 kJ

What is delta H for the formation of 8.00 g of O2 (mm = 32.0 g/mol)

• -189 kJ

• -22.2 kJ

• -94.5 kJ

• -47.2 kJ

• -300 kJ

Tags

NGSS.HS-PS3-1

Given the following reaction and its corresponding enthalpy of reaction, how many grams of Fe2O3 are produced when 5.62*10^3 kJ are released to the surroundings? Molar Mass (Fe2O3) = 159.7 g/mol

4 Fe (s) + 3 O2 (g) -> 2 Fe2O3 (s) delta Hrxn = -1.65*10^3 kJ

• 272 g Fe2O

• 1.09 *10^3 g Fe2O3

• 93.8 g Fe2O3

• 46.9 g Fe2O3

• 544 g Fe2O3

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

What is the specific heat of an unknown substance if 25.0 grams of the substance absorbs 77.0 calories of heat and the temperature increases by 5.5 °C?

• 0.51 cal/g×°C

• 0.62 cal/g×°C

• 0.28 cal/g×°C

• 0.48 cal/g×°C

• 0.56 cal/g×°C

Given the equations listed below and their corresponding enthalpies:

N2O4 (g) -> 2 NO2 (g) deltaH = 58 kJ

2 NO (g) + O2 (g) -> 2 NO2 (g) deltaH = -112 kJ

What is deltaH for the following reaction?

2 NO (g) + O2 (g) -> N2O4 (g)

• +54 kJ

• -112 kJ

• -54 kJ

• -170 kJ

• +170 kJ

Tags

NGSS.HS-PS1-4

Which of the following defines the heat of formation of Cr2O3 (s)?

• Cr2 (s) + 3 /2 O2 (g) ->Cr2O3 (s)

• 2 Cr (s) + 3 O (g) -> Cr2O3 (s)

• 4 Cr (s) + 3 O2 (g) -> 2 Cr2O3 (s)

• 2 Cr (s) + 3 /2 O2 (g) -> Cr2O3 (s)

• none of these

Tags

NGSS.HS-PS1-4

. Given the data below, what is DH° for the following reaction?

CH4 (g) + 3 Cl2 (g) -> CHCl3 (g) + 3 HCl (g)

deltaH°f [CH4 (g)] = -75 kJ/mol

deltaH°f [CHCl3 (g)] = -103 kJ/mol

deltaH°f [HCl (g)] = -92 kJ/mol

• -304 kJ

• +304 kJ

• +120 kJ

• -120 kJ

• + 208 kJ

Tags

NGSS.HS-PS1-4

A 5.0 mol sample of gas exerts a pressure of 2.0 atm at 27 °C in a certain container. What would be the pressure inside this container if 2.5 mol of the same gas are present at a temperature of 100 °C?

• 1.6 atm

• 3.7 atm

• 0.80 atm

• 1.2 atm

• 2.4 atm

How many moles of a gas occupy a volume of 5.0 L and exhibit a pressure of 775 torr at 25 °C?

• 4.8 moles

• 2.5 moles

• 0.21 moles

• 1900 moles

• 160 moles

How many grams of potassium chlorate, KClO3, decompose to form potassium chloride and 250. mL of O2 at 400 K and 0.850 atm? Molar Mass(KClO3) = 122.55 g/mol

2 KClO3 (s) -> 2 KCl (s) + 3 O2 (g)

• 4.76 g KClO3

• 1.19 g KClO3

• 0.00647 g KClO3

• 0.793 g KClO3

• 0.529 g KClO3