Calculations

Question 1

Percentage yield

Answer 1

Compares actual and theoretical yield

Actual yield grams / theoretical yield x 100

Question 2

Avogadro’s number = 1 mol

Answer 2

6.023 x 10 p23

Question 3

Calculating volumes

Answer 3

Avogadro’s law = one mole of any gas occupies 24dm3 or 24000 cm3 - at room temp 25oc + 1 atmospheric pressure.

So

Volume (dm3) = moles of gas x 24

Question 4

Electrolysis of aqueous solutions.

Answer 4

Also H+ and OH- ions

Cathode -, Hydrogen has if metal ions more reactive than H+ ions.

Anode +, OH- and no halides O2 forms and water:

4OH- => O2 + 2H2O + 4e-

Question 5

Electrolysis calculating masses

Answer 5

Use Q (coulombs) = I (amps) X time (s)

96000 = faraday

Balanced half equation.
Calc num of faradays
Calc number of moles of element (divide by electron num)
Work out mass

Question 6

How du increase amount of product?

Answer 6

Electrolyse for longer

Increase the current