Chemistry 1 Test 2 study questions

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Dr Masadeh Navarro College

According to the following balanced reaction, how many moles of NO are formed from 8.44 moles of NO2 if there is plenty of water present?

3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g)

2.81 moles NO

Consider the following reaction. How many moles of oxygen are required to produce 2.33 moles of water? Assume that there is excess C3H7SH present.

C3H7SH(l) + 6 O2(g) → 3 CO2(g) + SO2(g) + 4 H2O (g)

3.50 moles O2

According to the following balanced reaction, how many moles of KO are required to exactly react with 5.44 moles of H2O?

4 KO(s) + 2 H2O(l) → 4 KOH(s) + O2(g)

10.9 moles H2O

How many grams of Li3N can be formed from 1.75 moles of Li? Assume an excess of nitrogen.

6 Li(s) + N2(g) → 2 Li3N(s)

20.3 g Li3N

How many grams of oxygen are formed when 6.21 moles of KOH are formed?

4 KO(s) + 2 H2O(l) → 4 KOH(s) + O2(g)

49.7 g O2

How many moles of oxygen are formed when 58.6 g of KNO3 decomposes according to the following reaction? The molar mass of KNO3 is 101.11 g/mol.

4 KNO3(s) → 2 K2O(s) + 2 N2(g) + 5 O2(g)

0.724 mol O2

Consider the following balanced reaction. How many grams of water are required to form 75.9 g of HNO3? Assume that there is excess NO2 present. The molar masses are as follows: H2O = 18.02 g/mol, HNO3 = 63.02 g/mol.

3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g)

10.9 g H2O

Consider the following balanced reaction. What mass (in g) of CO2 can be formed from 288 mg of O2? Assume that there is excess C3H7SH present.

C3H7SH(l) + 6 O2(g) → 3 CO2(g) + SO2(g) + 4 H2O (g)

0.198 g CO2

According to the following reaction, how many grams of sulfur are formed when 37.4 g of water are formed?
2 H2S(g) + SO2(g) → 3 S(s) + 2H2O(l)

99.8 g S

How many molecules of HCl are formed when 50.0 g of water reacts according to the following balanced reaction? Assume excess ICl3.

2 ICl3 + 3 H2O → ICl + HIO3 + 5 HCl

2.78 × 1024 molecules HCl

How many molecules of H2S are required to form 79.0 g of sulfur according to the following reaction? Assume excess SO2.

2 H2S(g) + SO2(g) → 3 S(s) + 2H2O(l)

9.89 × 1023 molecules H2S

Carbonic acid can form water and carbon dioxide upon heating. How much carbon dioxide is formed from 6.20 g of carbonic acid?

H2CO3 → H2O + CO2

4.40 g

Determine the theoretical yield of H2S (in moles) if 4.0 mol Al2S3 and 4.0 mol H2O are reacted according to the following balanced reaction. A possibly useful molar mass is Al2S3 = 150.17 g/mol.

Al2S3 (s) + 6 H2O(l) → 2 Al(OH)3 (s) + 3 H2S(g)

2.0 mol H2S

A 14.01 g sample of N2 reacts with 3.02 g of H2 to form ammonia (NH3). If ammonia is the only product, what mass of ammonia is formed?

17.01 g

Give the theoretical yield, in moles, of CO2 from the reaction of 4.00 moles of C8H18 with 4.00 moles of O2.

2 C8H18 + 25 O2 → 16 CO2 + 18 H2O

2.56 moles

A 12.39 g sample of phosphorus reacts with 42.54 g of chlorine to form only phosphorus trichloride (PCl3). If it is the only product, what mass of PCl3 is formed?

54.93 g

Give the theoretical yield, in grams, of CO2 from the reaction of 4.000 moles of C8H18 with 4.000 moles of O2.

2 C8H18 + 25 O2 → 16 CO2 + 18 H2O

112.7 g

Determine the limiting reactant (LR) and the mass (in g) of nitrogen that can be formed from 50.0 g N2O4 and 45.0 g N2H4. Some possibly useful molar masses are as follows: N2O4 = 92.02 g/mol, N2H4 = 32.05 g/mol.

N2O4(l) + 2 N2H4(l) → 3 N2(g) + 4 H2O(g)

LR = N2O4, 45.7 g N2 formed

Determine the theoretical yield of HCl if 60.0 g of BCl3 and 37.5 g of H2O are reacted according to the following balanced reaction. A possibly useful molar mass is BCl3 = 117.16 g/mol.

BCl3(g) + 3 H2O(l) → H3BO3(s) + 3 HCl(g)

56.0 g HCl

According to the following reaction, what amount of Al2S3 remains when 20.00 g of Al2S3 and 2.00 g of H2O are reacted? A few of the molar masses are as follows: Al2S3 = 150.17 g/mol, H2O = 18.02 g/mol.

Al2S3(s) + 6 H2O(l) → 2 Al(OH)3(s) + 3 H2S(g)

17.22 g

Give the percent yield when 28.16 g of CO2 are formed from the reaction of 4.000 moles of C8H18 with 4.000 moles of O2.

2 C8H18 + 25 O2 → 16 CO2 + 18 H2O

25.00%

Determine the percent yield of a reaction that produces 28.65 g of Fe when 50.00 g of Fe2O3 react with excess Al according to the following reaction.

Fe2O3(s) + 2 Al(s) → Al2O3(s) + 2 Fe(s)

81.93 %

Which of the following solutions will have the highest concentration of chloride ions?

0.10 M AlCl3

Which of the following solutions will have the highest electrical conductivity?

0.045 M Al2(SO4)3

How many milliliters of a 0.184 M NaNO3 solution contain 0.113 moles of NaNO3?

614 mL

How many liters of a 0.0550 M KCl solution contain 0.163 moles of KCl?

2.96 L

How many moles of LiI are contained in 258.6 mL of 0.0296 M LiI solution?

7.65 × 10-3 mol

How many moles of CH3CH2OH are contained in 548 mL of 0.0788 M CH3CH2OH solution?

4.32 × 10-2 mol

How many moles of NaCl are required to make 250 mL of a 3.00 M solution?

0.750 moles

What is the concentration of nitrate ions in a 0.125 M Mg(NO3)2 solution?

0.250 M

How many milliliters of a 0.266 M LiNO3 solution are required to make 150.0 mL of 0.075 M LiNO3 solution?

42.3 mL

What volume (in mL) of 0.0887 M MgF2 solution is needed to make 275.0 mL of 0.0224 M MgF2 solution?

69.4 mL

Determine the concentration of a solution prepared by diluting 25.0 mL of a stock 0.188 M Ca(NO3)2 solution to 150.0 mL.

0.0313 M

Determine the molarity of a solution formed by dissolving 97.7 g LiBr in enough water to yield 750.0 mL of solution.

1.50 M

Determine the molarity of a solution formed by dissolving 468 mg of MgI2 in enough water to yield 50.0 mL of solution.

0.0337 M

How many grams of NaCl are required to make 250.0 mL of a 3.000 M solution?

43.83 g

How many molecules of sucrose (C12H22O11, molar mass = 342.30 g/mol) are contained in 14.3 mL of 0.140 M sucrose solution?

1.21 × 1021 molecules C12H22O11

How many chloride ions are present in 65.5 mL of 0.210 M AlCl3 solution?

2.48 × 1022 chloride ions

According to the following reaction, how many moles of Fe(OH)2 can form from 175.0 mL of 0.227 M LiOH solution? Assume that there is excess FeCl2.

FeCl2(aq) + 2 LiOH(aq) → Fe(OH)2(s) + 2 LiCl(aq)

1.99 × 10-2 moles

According to the following reaction, what volume of 0.244 M KCl solution is required to react exactly with 50.0 mL of 0.210 M Pb(NO3)2 solution?

2 KCl(aq) + Pb(NO3)2 (aq) → PbCl2(s) + 2 KNO3(aq)

86.1 mL

According to the following reaction, what mass of PbCl2 can form from 235 mL of 0.110 M KCl solution? Assume that there is excess Pb(NO3)2.

2 KCl(aq) + Pb(NO3)2 (aq) → PbCl2(s) + 2 KNO3(aq)

3.59 g

Determine the number of grams H2 formed when 250.0 mL of 0.743 M HCl solution reacts with 3.41 x 1023 atoms of Fe according to the following reaction.

2 HCl(aq) + Fe(s) → H2(g) + FeCl2(aq)

0.187 g

What volume of 0.305 M AgNO3 is required to react exactly with 155.0 mL of 0.274 M Na2SO4 solution? Hint: you will want to write a balanced reaction.

278 mL

What mass (in g) of AgCl is formed from the reaction of 75.0 mL of a 0.078 M AgC2H3O2 solution with 55.0 mL of 0.109 M MgCl2 solution?

2 AgC2H3O2(aq) + MgCl2(aq) → 2 AgCl(s) + Mg(C2H3O2)2(aq)

0.838 g

Which of the following is NOT a strong electrolyte?

MgCO3

Which of the following is considered a STRONG electrolyte?

NH4NO3

Choose the statement below that is TRUE.

A weak acid solution consists of mostly nonionized acid molecules.

How many of the following compounds are soluble in water?

Cu(OH)2 LiNO3 NH4Br K2S

3

Which of the following compounds is soluble in water?

CaS

Which of the following compounds is insoluble in water?

Hg2I2

What precipitate is most likely formed from a solution containing Ba+2, Na+1, OH-1, and CO3-2.

BaCO3

Energy that is associated with the position or composition of an object is called

potential energy

Which of the following signs on q and w represent a system that is doing work on the surroundings, as well as losing heat to the surroundings?

q = - , w = -

Which of the following signs on q and w represent a system that is doing work on the surroundings, as well as gaining heat from the surroundings?

q = +, w = -

Which of the following is TRUE if ΔEsys = - 95 J?

The system is losing 95 J, while the surroundings are gaining 95 J.

Calculate the change internal energy (ΔE) for a system that is giving off 45.0 kJ of heat and is performing 855 J of work on the surroundings.

-45.9 kJ

For ΔEsys to always be -, what must be true?

-w > +q

Calculate the change in internal energy (ΔE) for a system that is giving off 25.0 kJ of heat and is changing from 12.00 L to 6.00 L in volume at 1.50 atm pressure. (Remember that 101.3 J = 1 L∙atm)

-24.1 kJ

Calculate the change in internal energy (ΔE) for a system that is absorbing 35.8 kJ of heat and is expanding from 8.00 to 24.0 L in volume at 1.00 atm. (Remember that 101.3 J = 1 L·atm)

+34.2 kJ

A piece of iron (C=0.449 J/g°C) and a piece of gold (C=0.128 J/g°C) have identical masses. If the iron has an initial temperature of 498 K and the gold has an initial temperature of 298 K, which of the following statements is TRUE of the outcome when the two metals are placed in contact with one another? Assume no heat is lost to the surroundings.

Since the two metals have the same mass, but the specific heat capacity of iron is much greater than that of gold, the final temperature of the two metals will be closer to 498 K than to 298 K.

Which of the following substances (with specific heat capacity provided) would show the greatest temperature change upon absorbing 100.0 J of heat?

10.0 g Au, CAu = 0.128 J/g°C

Which of the following (with specific heat capacity provided) would show the smallest temperature change upon gaining 200.0 J of heat?

50.0 g Al, CAl = 0.903 J/g°C

Calculate the amount of heat (in kJ) required to raise the temperature of a 79.0 g sample of ethanol from 298.0 K to 385.0 K. The specific heat capacity of ethanol is 2.42 J/g°C.

16.6 kJ

Calculate the amount of heat (in kJ) necessary to raise the temperature of 47.8 g benzene by 57.0 K. The specific heat capacity of benzene is 1.05 J/g°C

2.86 kJ

Determine the specific heat capacity of an alloy that requires 59.3 kJ to raise the temperature of 150.0 g alloy from 298 K to 398 K.

3.95 J/g°C

A sample of copper absorbs 43.6 kJ of heat, resulting in a temperature rise of 75.0 °C, determine the mass (in kg) of the copper sample if the specific heat capacity of copper is 0.385 J/g°C.

1.51 kg

Determine the final temperature of a gold nugget (mass = 376 g) that starts at 398 K and loses 4.85 kJ of heat to a snowbank when it is lost. The specific heat capacity of gold is 0.128 J/g°C.

297 K

A 6.55 g sample of aniline (C6H5NH2, molar mass = 93.13 g/mol) was combusted in a bomb calorimeter. If the temperature rose by 32.9°C, use the information below to determine the heat capacity of the calorimeter.
4 C6H5NH2(l) + 35 O2(g) → 24 CO2(g) + 14 H2O(g) + 4 NO2(g)
ΔH°rxn= -1.28 x 104 kJ

6.84 kJ/°C

A 21.8 g sample of ethanol (C2H5OH) is burned in a bomb calorimeter, according to the following reaction. If the temperature rises from 25.0 to 62.3°C, determine the heat capacity of the calorimeter. The molar mass of ethanol is 46.07 g/mol.
C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(g) ΔH°rxn = -1235 kJ

15.7 kJ/°C

A 4.98 g sample of aniline (C6H5NH2, molar mass = 93.13 g/mol) was combusted in a bomb calorimeter with a heat capacity of 4.25 kJ/°C. If the temperature rose from 29.5°C to 69.8°C, determine the value of ΔH°comb for aniline.

-3.20 × 103 kJ/mol

The temperature rises from 25.00 °C to 29.00 °C in a bomb calorimeter when 3.50 g of sucrose undergoes combustion in a bomb calorimeter. Calculate ΔErxn for the combustion of sucrose in kJ/mol sucrose. The heat capacity of the calorimeter is 4.90 kJ/°C . The molar mass of sugar is 342.3 g/mol.

-1.92 x 103 kJ/mole

A 12.8 g sample of ethanol (C2H5OH) is burned in a bomb calorimeter with a heat capacity of 5.65 kJ/°C. Using the information below, determine the final temperature of the calorimeter if the initial temperature is 25.0°C. The molar mass of ethanol is 46.07 g/mol.
C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(g) ΔH°rxn = -1235 kJ

85.7 °C

A 35.6 g sample of ethanol (C2H5OH) is burned in a bomb calorimeter, according to the following reaction. If the temperature rose from 35.0 to 76.0°C and the heat capacity of the calorimeter is 23.3 kJ/°C, what is the value of DH°rxn? The molar mass of ethanol is 46.07 g/mol.
C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(g) ΔH°rxn = ?

-1.24 × 103 kJ/mol

A 6.55 g sample of aniline (C6H5NH2, molar mass = 93.13 g/mol) was combusted in a bomb calorimeter with a heat capacity of 14.25 kJ/°C. If the initial temperature was 32.9°C, use the information below to determine the value of the final temperature of the calorimeter.
4 C6H5NH2(l) + 35 O2(g) → 24 CO2(g) + 14 H2O(g) + 4 NO2(g)
ΔH°rxn= -1.28 x 104 kJ

48.7°C

Given w = 0, an endothermic reaction has the following.

+ ΔH and +ΔE

Which of the following processes is endothermic?

The vaporization of rubbing alcohol.

Which of the following processes is exothermic?

The formation of dew in the morning.

Which of the following processes is endothermic?

An atom absorbs a photon.

Using the following equation for the combustion of octane, calculate the heat of reaction for 100.0 g of octane. The molar mass of octane is 114.33 g/mole.
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O ΔH°rxn = -11018 kJ

4.82 x 103 kJ

How much energy is required to decompose 765 g of PCl3, according to the reaction below? The molar mass of PCl3 is 137.32 g/mol and may be useful.
4 PCl3(g) → P4(s) + 6 Cl2(g) ΔH°rxn = +1207 kJ

1.68 × 103 kJ

How much energy is evolved during the reaction of 48.7 g of Al, according to the reaction below? Assume that there is excess Fe2O3.
Fe2O3(s) + 2 Al(s) → Al2O3(s) + 2 Fe(s) ΔH°rxn = -852 kJ

769 kJ

How much energy is evolved during the formation of 98.7 g of Fe, according to the reaction below?
Fe2O3(s) + 2 Al(s) → Al2O3(s) + 2 Fe(s) ΔH°rxn = -852 kJ

753 kJ

According to the following reaction, how much energy is required to decompose 55.0 kg of Fe3O4? The molar mass of Fe3O4 is 231.55 g/mol.
Fe3O4(s) → 3 Fe(s) + 2 O2(g) ΔH°rxn = +1118 kJ

2.66 × 105 kJ

Using the following thermochemical equation, determine the amount of heat produced per kg of CO2 formed during the combustion of benzene (C6H6).
2 C6H6(l) + 15 O2(g) → 12 CO2(g) + 6 H2O(g) ΔH°rxn = -6278 kJ

1.19 × 104 kJ/kg CO2

Using the following equation for the combustion of octane, calculate the amount of moles of carbon dioxide formed from 100.0 g of octane. The molar mass of octane is 114.33 g/mole. The molar mass of carbon dioxide is 44.0095 g/mole.
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O ΔH°rxn = -11018 kJ

6.997 moles

According to the following reaction, how much energy is evolved during the reaction of
32.5 g B2H6 and 72.5 g Cl2? The molar mass of B2H6 is 27.67 g/mol.
B2H6(g) + 6 Cl2(g) → 2 BCl3(g) + 6 HCl(g) ΔH°rxn = -1396 kJ

238 kJ

According to the following reaction, how much energy is evolved during the reaction of
2.50 L B2H6 and 5.65 L Cl2 (Both gases are initially at STP)? The molar mass of B2H6 is 27.67 g/mol.
B2H6(g) + 6 Cl2(g) → 2 BCl3(g) + 6 HCl(g) ΔH°rxn = -1396 kJ

58.7 kJ

According to the following thermochemical equation, what mass of HF (in g) must react in order to produce 345 kJ of energy? Assume excess SiO2.
SiO2(s) + 4 HF(g) → SiF4(g) + 2 H2O(l) ΔH°rxn = -184 kJ

150. g

According to the following thermochemical equation, what mass of H2O (in g) must form in order to produce 975 kJ of energy?
SiO2(s) + 4 HF(g) → SiF4(g) + 2 H2O(l) ΔH°rxn = -184 kJ

191 g

Using the following equation for the combustion of octane, calculate the amount of grams of carbon dioxide formed from 100.0 g of octane. The molar mass of octane is 114.33 g/mole. The molar mass of carbon dioxide is 44.0095 g/mole.
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O ΔH°rxn = -11018 kJ

307.9 g

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