Enthalpy changes and Hess's law

Question 1 of 10

The temperature of 100 g of water rises by 10 °C. How much heat was absorbed? (c = 4.2 J g⁻¹ °C⁻¹)

Question 2 of 10

The temperature of 50 g of water rises by 8 °C. How much heat was absorbed? (c = 4.2 J g⁻¹ °C⁻¹)

Question 3 of 10

In an experiment, 0.92 g of ethanol (C₂H₅OH, M = 46) was burned to heat 100 g of water. The temperature of the water rose by 26 °C. (c = 4.2 J g⁻¹ °C⁻¹) (a) Calculate the heat absorbed by the water. (b) Calculate the moles of ethanol burned. (c) Calculate the enthalpy of combustion of ethanol. (d) Give two reasons why the value is less than the data-book value of −1,367 kJ/mol.

Question 4 of 10

In an experiment, 0.23 g of ethanol (C₂H₅OH, M = 46) was burned to heat 250 g of water. The temperature of the water rose by 2.6 °C. (c = 4.2 J g⁻¹ °C⁻¹) (a) Calculate the heat absorbed by the water. (b) Calculate the moles of ethanol burned. (c) Calculate the enthalpy of combustion of ethanol. (d) Give two reasons why the value is less than the data-book value of −1,367 kJ/mol.

Question 5 of 10

Given A → B, ΔH₁ = −286 kJ, and B → C, ΔH₂ = −283 kJ, find ΔH for A → C.

Question 6 of 10

Heat absorbed when 100 g of water warms by 10 °C (c = 4.2 J g⁻¹ °C⁻¹) is ___ J.

Question 7 of 10

Heat absorbed when 100 g of water warms by 4 °C (c = 4.2 J g⁻¹ °C⁻¹) is ___ J.

Question 8 of 10

In an experiment, 0.46 g of ethanol (C₂H₅OH, M = 46) was burned to heat 200 g of water. The temperature of the water rose by 6.5 °C. (c = 4.2 J g⁻¹ °C⁻¹) (a) Calculate the heat absorbed by the water. (b) Calculate the moles of ethanol burned. (c) Calculate the enthalpy of combustion of ethanol. (d) Give two reasons why the value is less than the data-book value of −1,367 kJ/mol.

Question 9 of 10

In an experiment, 0.92 g of ethanol (C₂H₅OH, M = 46) was burned to heat 250 g of water. The temperature of the water rose by 10.4 °C. (c = 4.2 J g⁻¹ °C⁻¹) (a) Calculate the heat absorbed by the water. (b) Calculate the moles of ethanol burned. (c) Calculate the enthalpy of combustion of ethanol. (d) Give two reasons why the value is less than the data-book value of −1,367 kJ/mol.

Question 10 of 10

The enthalpy of neutralisation of a weak acid is less exothermic because