chem quiz 2

Question 1

A student has 3 different metals. They want to investigate how the different types of metals cause a different temperature change when added to an acid. Outline a method to do this. Ensure the method leads to a valid conclusion

Answer 1

Measure a specific mass of the first metal

use a measuring cylinder to measure a set volume of acid and pour into polystyrene cup

Measure the temperature of the acid

Add the first metal to the acid

Measure the highest temperature reached by the acid

Repeat the experiment with the other two metals

Ensure that the following variables are kept constant: mass of metal, particle size of metal, volume of acid, concentration of acid

Question 2

A student is adding metal carbonate to acid at a range of different concentrations to measure the rate of reaction. Name the independent variable

Answer 2

concentration of acid

Question 3

Explain why Mendeleev put some elements in groups and changed the weight based order

Answer 3

to group the elements, based on their properties

Question 4

In this reaction, what has been oxidised and what has been reduced?
Mg2+ + 2Na ——-> 2Na + Mg

Answer 4

Mg2+ has been oxidised
Na has been oxidised

Question 5

A student is adding metal carbonate to acid at a range of different temperatures to measure the rate of reaction. Name the dependent variable

Answer 5

change in mass or volume of gas produced at different times

Question 6

In terms of bond energies, explain why some reactions are exothermic

Answer 6

less energy is released when forming bonds in the products than is taken in to break the bonds in the reactants

Question 7

In electrolysis, what types of substances can be electrolytes?

Answer 7

ionic compounds that have been melted or dissolved in water

Question 8

Give a half equation to show the formation of oxygen(positive electrode) at the anode during electrolysis of a solution

Answer 8

4OH ——–> O2 + 2H2O + 4e-