Calculating Heat and Enthalpy Changes

A 15.75-g piece of iron absorbs 1086.75 joules of heat energy, and its temperature changes from 25°C to 175°C.  Calculate the specific heat capacity of iron.    

• 0.46 J/gx^oC
• 1.654 J/gx^oC
• 2,567,446.875 J/gx^oC

 How many joules of heat are needed to raise the temperature of 10.0 g of aluminum from 22°C to 55°C, if the specific heat of aluminum is 0.90 J/gx°C?    

• 297 Joules
• 0.003 Joules
• 297 J/gx°C
• 0.003 J/gx°C

When a  piece of aluminum foil is taken out of the oven and cools from 100° to 50°, What is the change in temperature?

• 50°
• 0°
• 100°
• 150°

The symbol for specific heat is .......

• c
• Q
• m
• t

20 g of water. specific heat of water is 4.18 J/x°C. temperature changes from 25° C to 20° C, how much heat energy moves from the water to the surroundings?

• 418 Joules

• 209 J

• 83 J

• 4.18 J

The specific heat of copper is 0.39 J/g °C. What is the temperature change when 100 Joules of heat is added to 20 grams?

• 12.82 °C

• 24.12°C

• 351 °C

The standard enthalpy changes of formation of carbon dioxide and of methanoic acid are −394 kJ/mol and −409 kJ/mol respectively. Calculate the enthalpy change for the reaction

H_{2 (g)} + CO_{2 (g)} → HCOOH _(l)

• −803 kJ/mol

• −15 kJ/mol

• +803 kJ/mol

• +15 kJ/mol

ΔH value in an endothermic reaction is a positive number.

• True
• False

Calculate the change in Enthalpy of the combustion reaction of liquid Ethanol (C2H5OH). When Ethanol has an enthalpy of -286 kJ/ mol, water is liquid and oxygen and carbon dioxide are in gas state.

• -286 kJ/ mol

• 1366 kJ/mol

• -2732 kJ/ mol

• -1366 kJ/mol

The standard enthalpy change for the combustion of graphite is −393.5 kJ/mol and that of diamond is −395.4 kJ/mol.

What is the enthalpy change for the reaction below, in kJ/mol?

C _{(s, graphite)} → C _{(s, diamond)}

• −1.9

• +1.9

• −788.9

• +788.9