Worksheet: Using Calorimetry Measurements

In this worksheet, we will practice using the specific heat of a material to calculate the mass, temperature change, or amount of heat exchanged.

Q1:

When 2.0 g of fructose, CHO()6126s, a sugar commonly found in fruits, is burned in oxygen in a bomb calorimeter, the temperature of the calorimeter increases by 3.16โˆ˜C.

If the heat capacity of the calorimeter and its contents is 9.90/kJCโˆ˜, calculate the heat released by this combustion, ๐‘ž, to 2 significant figures.

From the value of ๐‘ž, calculate the molar enthalpy of combustion for fructose to 2 significant figures.

Q2:

The addition of 3.15 g of Ba(OH)ยท8HO22 to a solution of 1.52 g of NHSCN4 in 100 g of water in a calorimeter caused the temperature to fall by 3.1โˆ˜C. Assuming the specific heat of the solution and products is 4.20/โ‹…JgCโˆ˜, what is the approximate amount of heat absorbed by the reaction? Give your answer in kilojoules to two significant figures.

The reaction can be represented by the following equation.

B a ( O H ) ยท 8 H O ( ) + 2 N H S C N ( ) B a ( S C N ) ( ) + 2 N H ( ) + 1 0 H O ( ) 2 2 4 2 3 2 ๐‘  ๐‘Ž ๐‘ž ๐‘Ž ๐‘ž ๐‘Ž ๐‘ž ๐‘™

Q3:

When a 3.00 g sample of KCl was added to 3.00ร—10๏Šจ g of water in a coffee cup calorimeter, the temperature decreased by 1.05โˆ˜C. How much heat is involved in the dissolution of the KCl? Assume that the specific heat of the solution is 4.184/โ‹…JgCโˆ˜.

Q4:

To 3 significant figures, how much heat energy is required to heat a 28.4 g ice cube from โˆ’21.0โˆ˜C to โˆ’2.0โˆ˜C? The specific heat capacity of ice is 2.108/โ‹…JgCโˆ˜

Q5:

How much would the temperature of 285 g of water increase if 36.5 kJ of heat were added? The specific heat capacity of water is 4.184/โ‹…JgCโˆ˜.

Q6:

If 14.5 kJ of heat were added to 515 g of liquid water, how much would its temperature increase? Assume that the specific heat of water is 4.186/โ‹…JgCโˆ˜.

Q7:

A 600 mL bottle of water at room temperature and a 2 L bottle of water at the same temperature were placed in a refrigerator. After 30 minutes, the 600 mL bottle of water had cooled to the temperature of the refrigerator. An hour later, the 2 L of water had cooled to the same temperature.

Which sample of water lost the most heat?

  • AThe 2 L bottle of water lost more heat because a greater mass of water was cooled.
  • BThe bottles lost the same amount of heat because they started at the same temperature and finished at the same temperature.
  • CThe 600 mL bottle of water lost more heat because it cooled more quickly.
  • DIt is not possible to determine which bottle lost the most heat because we do not know the initial temperature and the final temperature of the water.

Q8:

How much energy is required to heat 300 g of water from 4.2โˆ˜C to 25.0โˆ˜C and immediately evaporate the liquid? Use values of 4.1813 J/gโ‹…K for the specific heat capacity of water and 43.5 kJ/mol for the enthalpy of vaporization. Give your answer to three significant figures.

Q9:

The enthalpy change when calcium chloride (CaCl)2 dissolves in water is โˆ’82.9 kJ/mol. The heat capacity of the solution is approximately equal to that of water (๐‘=4.18/โ‹…)JgK. If 90 g of CaCl2 dissolves in 5.0 L of water at 20โˆ˜C, what is the temperature of the resulting solution?

Q10:

The melting enthalpy of ice is 6.01 kJ/mol. At 0.00โˆ˜C, combustion of 10.0 g of butane (CH)410 releases sufficient heat to melt 1.20 kg of ice and increase the temperature of the resulting water (๐‘ = 4.184 J/gโ‹…K) to 18.9โˆ˜C. What is the enthalpy of combustion of butane?

  • A โˆ’ 2 . 9 ร— 1 0 ๏Šฉ kJ/mol
  • B โˆ’ 5 . 5 ร— 1 0 ๏Šฉ kJ/mol
  • C โˆ’ 2 . 4 ร— 1 0 ๏Šฉ kJ/mol
  • D โˆ’ 1 . 3 ร— 1 0 ๏Šฉ kJ/mol
  • E โˆ’ 2 . 3 ร— 1 0 ๏Šฉ kJ/mol

Q11:

Aqueous iron(II) chloride (FeCl)2 and hydrogen peroxide (HO)22 react in excess dilute hydrochloric acid according to the equation: FeCl()+12HO()+HCl()FeCl()+HO()22232aqaqaqaql. The enthalpy change for this reaction is โˆ’149 kJ/mol. At 20.0โˆ˜C, solutions containing 1.901 g of FeCl2 and 0.260 g of HO22 in 1 M aqueous HCl are mixed in an insulated container. The final solution has a volume of 100 cm3, a density of 1.000 g/cm3, and a specific heat of 4.184 J/gโ‹…K. Calculate, to 1 decimal place, the temperature of the solution at the end of the reaction.

Q12:

Natural gas is mostly methane. Burning natural gas in air is a highly efficient way of generating heat.

Methane combusts completely in air according to the following equation: CH+2OCO+HO4222. The combustion of 10.0 mmol of methane and excess oxygen heats a small amount of water in a bomb calorimeter by 21.1โˆ˜C. The water has a mass of 100 g and specific heat of 4.184/โ‹…JgCโˆ˜. Assuming the water absorbs all heat generated by the reaction, calculate the molar enthalpy of combustion of methane.

Q13:

Aqueous sodium periodate (NaIO)4 reacts with aqueous hydroiodic acid (HI) according to the equation: NaIO()+2HI()NaIO()+I()+HO()4322aqaqaqaql.

The enthalpy change for this reaction is โˆ’493 kJ/mol and the enthalpy of solution for NaIO4 is โˆ’55.2 kJ/mol. At 20.0โˆ˜C, 1.85 g of NaIO4 is dissolved in 150 cm3 of 0.100 M aqueous HI in an insulated container. It is assumed that the solution has a density of 1.00 g/cm3 and specific heat of 4.184 J/gโ‹…K and that the mass of solute is negligible. By identifying the limiting reagent and determining the total heat absorbed or released by the solution, calculate the temperature of the solution at the end of the reaction to 1 decimal place.

Q14:

How much heat is produced by the combustion of 150 g of methanol under standard conditions? The standard enthalpy of combustion for methanol is โˆ’726.1 kJ/mol.

Q15:

The standard enthalpy of combustion of acetylene is โˆ’1,301.1 kJ/mol. How much heat is produced by the combustion of 4.0000 moles of acetylene under standard conditions?

Q16:

When 2.50 g of methane burns in oxygen, 125 kJ of heat is produced. What is the molar enthalpy of combustion of methane?

Q17:

The standard enthalpy of combustion of isooctane is โˆ’5,461 kJ/mol. How many moles of isooctane must be burned to release 100 kJ of heat under standard conditions?

Q18:

Ethanol can be used as a fuel, either as an additive to gasoline or in pure form. Complete combustion of 50.0 mL of ethanol releases 906 kJ of heat under standard conditions. Given that the density of ethanol is 0.789 g/mL, what is the standard molar enthalpy of combustion of ethanol?

Q19:

Aqueous sodium hydroxide (NaOH) and hydrochloric acid (HCl) react according to the equation: NaOH()+HCl()NaCl()+HO()aqaqaql2. At 20.00โˆ˜C, 4.00 g of NaOH in 100 cm3 of water is added to 100 cm3 of 1.50 M aqueous HCl. The temperature of the resulting solution is 26.87โˆ˜C.

What is the enthalpy change for this reaction? Assume, for all solutions, that the heat capacity is 4.184 J/gโ‹…K and the density is 1.00 g/cm3.

Q20:

Aqueous sodium hydroxide (NaOH) reacts with aqueous phosphoric acid (HPO)34 according to the equation: NaOH()+13HPO()13NaPO()+3HO()aqaqaql34342. The enthalpy change for this reaction is โˆ’52.0 kJ/mol. When 1.52 g of solid NaOH is dissolved in 300 cm3 of 0.100 M aqueous HPO34, the temperature of the solution changes from 20.00โˆ˜C to 22.60โˆ˜C. The solution has a density of 1.00 g/cm3 and specific heat of 4.184 J/gโ‹…K and absorbs all heat generated by the reaction. What is the enthalpy of solution for NaOH, to 2 significant figures?

Q21:

An insulated cup contains 100 mL of water at 0โˆ˜C. When this water is warmed, its density and specific heat remain approximately constant. Which of the following, if poured into the cup, would increase the temperature of its contents by the largest amount?

  • A5 mL of water at 100โˆ˜C
  • B20 mL of water at 60โˆ˜C
  • C10 mL of water at 80โˆ˜C
  • D80 mL of water at 20โˆ˜C
  • E40 mL of water at 40โˆ˜C

Q22:

An insulating bucket contains 3.00 kg of sand (๐‘=0.92/โ‹…)JgCโˆ˜ mixed with 900 g of water (๐‘=4.18/โ‹…)JgCโˆ˜. The mixture cools uniformly by 12.0โˆ˜C overnight. To 2 significant figures, how much heat has been released by the mixture?

Q23:

A 250 g potato at 25.0โˆ˜C is added to 1.50 L of oil at 80.0โˆ˜C. The oil has a density of 0.875 g/mL and a specific heat capacity of 1.67 J/gโ‹…K. The final temperature of the oil and the potato is 64.5โˆ˜C. To two significant figures, what is the specific heat capacity of the potato?

Q24:

A solid zinc catalyst (๐‘=0.387/โ‹…)JgK suspended in a toluene solution (๐‘=1.970/โ‹…)JgK makes up 10% of the total mass. A reactor supplies 50.0 MJ of energy to the suspension, increasing its temperature by 50.0โˆ˜C. To 2 significant figures, what is the total mass of the suspension?

Q25:

A 30.0 g block of aluminum is heated from 20.0โˆ˜C to 85.0โˆ˜C and placed into 100 g of 20.0โˆ˜C water. The specific heat of aluminum is 0.902/โ‹…JgCโˆ˜ and that of water is 4.184/โ‹…JgCโˆ˜. Calculate, to the nearest โˆ˜C, the temperature of the water and aluminum at equilibrium.

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