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Chemistry Straighterline Questions and Answers 2024
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Chemistry Straighterline
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Chemistry StraighterlineAn endothermic reaction causes the surroundings to:
A. warm up
B. becomes acidic
C. condenses
D. decrease in temperature
E. release CO2 – answer D
An exothermic reaction causes the surroundings to:
A. warm up
B. becomes acidic
C. expands
D. decrease its temperature
E. release CO2 - answer A
Copper metal has a specific heat of 0.385 J/g•oC and has a melting point of 1083oC.
calculate the amount of heat required to raise the temperature of 22.8 g of Cu from
20.0oC to 875oC.
A. 1.97 10 ─ 5 J
B. 1.0 10 ─ 2 J
C. 329 J
D. 7.51 kJ
E. 10.5 kJ - answerD
Calculate the amount of heat necessary to raise the temperature of 12.0 kg of water
from 15.4oC to 93.0oC.
A. 0.027 kJ B. 324 kJ C. 389 kJ D. 931 kJ
E. 3890 kJ - answerE
How much heat is required to raise the temperature of 1500 g of water from 25oC
to 52oC?
A. 1500 kJ B. 169 kJ C. 6.27 kJ D. 40.5 J E. 40.5 kJ - answerB
How many degrees of temperature rise will occur when a 25.0 g block of aluminum
absorbs 10 kJ of heat? The specific heat of Al is 0.900 J/g•oC.
A. 0.44oC B. 22.5oC C. 225oC D. 360oC E. 444oC - answerE
If 325 g of water at 4.2oC absorbs 12.28 kJ, then what is the final temperature of the
water?
A. 4.21oC B. 4.8oC C. 9.0oC D. 13.2oC E. 2938oC - answerD
,A glass containing 200 g of H2O at 20oC was placed into a refrigerator. The water loses
11.7 kJ as it cools to a constant temperature. What is its new temperature?
A. 0.013oC B. 4oC C. 6oC D. 14oC E. 34oC - answerC
A piece of copper with a mass of 218 g has a heat capacity of 83.9 J/oC. What is the
specific heat of copper?
A. 0.385 J/g•oC B. 1.83 ´ 104 J/g•oC C. 2.60 J/g•oC D. 1.32 J/g•oC
E. 24.5 J/g•oC - answerA
The specific heat of gold is 0.129 J/g•oC. What is the molar heat capacity of gold (unit is
J/mol•oC)?
A. 0.039 J/mol•oC
B. 0.129 J/mol•oC
C. 25.4 J/mol•oC
D. 39.0 kJ/mol•oC
E. 197 J/mol•oC - answerC
When 0.7521 g of benzoic acid was burned in a calorimeter containing 1000 g of water,
a temperature rise of 3.60oC was observed. What is the heat capacity of the bomb
calorimeter, excluding water? The heat of combustion of benzoic acid is ─26.42 kJ/g.
A. 15.87 kJ/oC
B. 4.18 kJ/oC
C. 5.52 kJ/oC
D. 1.34 kJ/oC
E. 752.1 kJ/oC - answerD
Naphthalene combustion can be used to determine the heat capacity of a bomb
calorimeter. The heat of combustion of naphthalene is 40.1 kJ/g. When 0.8210 g of
naphthalene was combusted in a calorimeter containing 1000 g of water a temperature
rise of 4.21oC was observed. What is the heat capacity of the bomb calorimeter
excluding the water?
A. 32.9 kJ/oC
B. 7.8 kJ/oC
C. 1.76 kJ/oC
D. 1.76 kJ/oC
E. 15.3 kJ/oC - answerC
Which of the following processes is endothermic?
a. O2(g) + 2H2(g) 2H2O(g)
b. H2O(g) H2O(l)
c. 3O2(g) + 2CH3OH(g) 2CO2(g) + 2H2O(g)
d. H2O(s) H2O(l) - answerD
A 100 mL sample of 0.200 M aqueous hydrochloric acid is added to 100 mL of 0.200 M
aqueous ammonia in a calorimeter whose heat capacity is 480 J K ─ 1. The following
reaction occurs when the two solutions are mixed.
,HCl(aq) + NH3(aq) NH4Cl(aq)
The temperature increase is 2.34oC. Calculate ΔH per mole of HCl neutralized.
A. 154 kJ B. 44.5 kJ C. 22.5 kJ D. ─22.5 kJ E. ─56.2 kJ - answerE
A 0.1326 g sample of magnesium was burned in an oxygen bomb calorimeter. The
Htotal heat capacity of the calorimeter plus water was 5760 J/oC. If the temperature rise
of the calorimeter with water was 0.570oC, calculate the enthalpy of combustion of
magnesium.
Mg(s) + 1/2O2(g) MgO(s)
A. ─3280 kJ/mol B. ─24.8 kJ/mol C. 435 kJ/mol
D. 106 kJ/mol E. ─602 kJ/mol - answerE
Which one of the following reactions occurring at 25oC does the symbol ΔHof[H2SO4(l)]
refer to?
A. 2H(g) + S(g) + 4O(g) H2SO4(l)
B. H2(g) + S(g) + 2O2(g) H2SO4(l)
C. H2SO4(l) H2(g) + S(s) + 2O2(g)
D. H2SO4(l) 2H(g) + S(s) + 4O(g)
E. H2(g) + S(s) + 2O2(g) H2SO4(l) - answerE
Which one of the following reactions occurring at 25oC does the symbol ΔHof[HNO3(l)]
refer to?
A. H(g) + N(g) + O3(g) HNO3(l)
B. 1/2H2(g) + 1/2N2(g) + 3/2O2(g) HNO3(l)
C. HNO3(l) 1/2H2(g) + 1/2N2(g) + 3/2O2(g)
D. HNO3(l) H(g) + N(g) + 3O(g)
E. H2(g) + N2(g) + O3(g) HNO3(l) - answerB
When 0.56 g of Na(s) react with excess F2(g) to form NaF(s) at standard state
conditions, 13.8 kJ of heat
are evolved. What is the standard enthalpy of formation (ΔHof) of NaF(s)?
A. 24.8 kJ/mol B. +570 kJ/mol C. ─24.8 kJ/mol D. ─7.8 kJ/mol
E. ─570 kJ/mol - answerE
Ethanol undergoes combustion according to the equation:
C2H5OH(l) + O2(g) CO2(g) + H2O(l) (Not Balanced)
The standard heat of combustion of ethanol, C2H5OH(l), is ─1366.8 kJ/mol. Given that:
ΔHof[CO2(g)] = ─393.5 kJ/mol
ΔHof[H2O(l)] = ─285.8 kJ/mol
What is the standard enthalpy of formation of ethanol?
A. 3010 kJ
B. ─687.6 kJ
C. ─277.6 kJ
D. 687.6 kJ
E. 1367 kJ - answerC
, Find the standard enthalpy of formation of ethylene, C2H4(g), given the following data:
C2H4(g) + 3O2(g) 2CO2(g) + 2H2O(l) ΔHof = ─1411 kJ
C(s) + O2(g) CO2(g) ΔHof = ─393.5 kJ
H2(g) + 1/2O2(g) H2O(l) ΔHof = ─285.8 kJ
A. 52 kJ
B. 87 kJ
C. 731 kJ
D. 1.41 103 kJ
E. 2.77 103 kJ - answerA
Octane (C8H18) undergoes combustion according to the following thermochemical
equation:
2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O(l) ΔHorxn = ─11,020 kJ.
Given that: ΔHof[CO2(g)] = ─393.5 kJ/mol
ΔHof[H2O(l)] = ─285.8 kJ/mol
Calculate the enthalpy of formation of 1 mole of octane.
A. ─210 kJ B. ─11,230 kJ C. 22,040 kJ D. ─420 kJ E. 420 kJ - answerA
Glycine C2H5O2N is important for biological energy. The combustion of glycine is given
by the equation,
4C2H5O2N(s) + 9O2(g) 8CO2(g) + 10H2O(l) + 2N2(g) ΔHorxn = ─3857 kJ
Given that ΔHof[CO2(g)] = ─393.5 kJ/mol, and ΔHof[H2O(l)] = ─285.8 kJ/mol. Calculate
the enthalpy of formation ΔHof per mole of glycine.
A. ─537.2 kJ/mol
B. ─268.2 kJ/mol
C. 2149 kJ/mol
D. ─3178 kJ/mol
E. ─964 kJ/mol - answerA
Calculate ΔHorxn for the following reaction.
2H2O2(l) 2H2O(l) + O2(g)
Use the following information:
ΔHof (H2O2(l)) = -187.6 kJ/mol ; ΔHof (H2O(l)) = -285.8 kJ/mol ; ΔHof (O2(g)) = 0
kJ/mol
A. 53.0 kJ B. 98.2 kJ C. -98.2 kJ D. 196.4 kJ E. ─196.4 kJ - answerE
Given 2Al(s) + 3/2O2(g) Al2O3(s) ΔHof = ─1670 kJ
What is ΔH for the reaction?
2Al2O3(s) 4Al(s) + 3O2(g) ΔHorxn = ?
A. 3340 kJ B. 1670 kJ C. ─3340 kJ D. ─1670 kJ E. ─835 kJ - answerA
Calculate the enthalpy change for the reaction:
C(graph) + 2H2(g) + 1/2O2(g) CH3OH(l)
Using the following information:
C(graph) + O2 CO2(g) ΔHof = ─393.5 kJ.
H2(g) + 1/2O2 H2O(l) ΔHof = ─285.8 kJ.
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