Equilibrium - 5th

Question 1

what are reversible chemical reactions?

Answer 1

they can go backwards as well as forwards

Question 2

example of a reversible reaction

Answer 2

the decomposition of N2O4

Question 3

what does whether a reversible reaction go forwards or backwards depend on?

Answer 3

the amount of reactants and products and the conditions (such as temperature and pressure)

Question 4

what does the decomposition of the above reaction show?

Answer 4

• forwards (colourless to brown)
• backwards (brown to colourless)

Question 5

what is the enthalpy change for a reversible reaction?

Answer 5

• refers to the forwards reaction
• for the backwards reaction, delta h is the same

Question 6

what is the dehydration of copper sulfate?

Answer 6

• a classic reversible reaction
• CuSO4 . 5H2O <-> CuSO4 + 5H2O

Question 7

how to make the reaction of the dehydration of copper sulfate go forwards?

Answer 7

• you heat hydrated copper sulfate (CuSO4 . 5H2O)
• the crystals turn from blue to white as they lose all their water

Question 8

how to make the reaction of the dehydration of copper sulfate go backwards?

Answer 8

• you add water to anhydrous copper sulfate (CuSO4)
• the white powder absorbs the water and turns blue in the process

Question 9

what is another example of a reversible reaction?

Answer 9

• the thermal decomposition of ammonium chloride (NH4Cl)
• NH4Cl (s) <-> NH3 (g) + HCl (g)

Question 10

how do you make the reaction go forwards?

Answer 10

• you heat NH4Cl (s)
• nothing appears to change, because NH3 and HCl are both colourless gases

Question 11

how do you make the reaction go backwards?