The molar mass of magnesium is 24 g. State the mass of 0.5 moles of magnesium.
2 points
2
Question 2
2.
The molar mass of silver is 108 g. How many atoms are in 5 moles of silver? (i) State how this can be calculated (ii) Do the calculation and give your answer.
3 points
3
Question 3
3.
A chemist reacts 16 g of Fe2O3 in the thermite reaction as shown: Fe2O3 + 2Al → 2Fe + Al2O3 (i) describe the steps the chemist should take to calculate the mass of iron produced in this reaction. (ii) Calculate the mass of iron produced when 16 g of Fe2O3 reacts. Show as much working as possible. (molar masses: Fe = 56, O = 16) *
2 points
2
Question 4
4.
Calculate the specific heat capacity of copper given that 204.75 J of energy raises the temperature of 15 g of copper from 25°C to 60°C. Show as much working as possible.
2 points
2
Question 5
5.
The theoretical enthalpy change for a chemical reaction can be calculated using the mean bond enthalpies. Describe the steps that you would take to calculate the enthalpy change for the following reaction: N2 + H2 → NH3
2 points
2
Question 6
6.
Using the mean bond enthalpies given below, calculate the overall enthalpy change for the following reaction: N2 + H2 → NH3 Show your working where possible.
2 points
2
Question 7
7.
In an experiment to determine the standard enthalpy change for the combustion of propan-1-ol, C3H7OH, a student used the apparatus shown below.
The student measured 50.0 cm3 of water into the beaker and lit the burner. When the temperature of the water had gone up by 12.8 °C, he found that 0.100 g of propan-1-ol had been burnt.
(a) Calculate the energy, in kJ, produced by burning 0.100 g of propan-1-ol. The specific heat capacity of water is 4.18 J g–1 K–1. Show as much working as possible.
2 points
2
Question 8
8.
(b) Calculate the number of moles of propan-1-ol in 0.100 g. Show as much working as possible. (molar masses: C = 12, H = 1, O = 16)
2 points
2
Question 9
9.
(c) Calculate the enthalpy change of combustion, in kJ mol–1 of propan-1-ol. Show as much working as possible.
2 points
2
Question 10
10.
(d) The student looked in a text book and found that the actual value for the standard enthalpy change of combustion of propan-1-ol was more exothermic than the experimental value. Suggest two reasons for the difference between this value and the one obtained experimentally.