paper 1 questions redo

H+ A-/ HA

Sulfurous acid = H2SO3

Dissassociates into H+ and HSO3- and then H+ and SO32-

Divide 0.0611/2 and plug into H+ = - log (10)(ph)

1. Calculate Ka 

2. Calculate pH before acid added suing Ka and initial concentration of A- and HA 

3. Calculate initial moles of HA, A- and Acid Added 

4. FInal moles of acid added = 0 

5. Calculate change in moles using change in moles of acid added (assume 1:1:1 ratio) 

6. Using final moles  calculate concentration of HA and A- 

7. Plug into H+ = K x HA/A - and then  work out final pH (pH = - Log (10) (h+) 

8. Final pH - Initial pH = Change in PH

9. answer = 0.08

1. Recognise that Burgundy mixture is made of ½ Na2CO2 and ½ Copper Sulfate 

2. Moles of Hcl = Moles of Burgundy Misture

3. ½ moles of HCL = ½ moles of Na2CO3 (base) 

4. Calculare moles of HCl 

5. Calculate moles of Na2CO3 (½ Hcl)

6. Scale up to 250 

7. Calculate mass of Na2Co3

8. Calculate mass of CuSO4 ( mass of burgundy - mass of Na2CO3)

9. Mass of Cu2+ ions by (mass of CUsO4 x Mr of Cu/ Mr od CuSO4)

   

if we use nomral method the mr of hydrated salt is less than moles of salt. We have tp divide scaled up moles by 2 because we found the moles of Al3+ but the formula unit is Al2 (SO4)3 so we need to divide by 2

1. moles of NaOH (A-)

2. Moles of HA (butanoic acid)

3. Moles of HA after A- added = Moles of NaOH - Moles of A-

4. Sub values into H+ = Ka x HA/A-

5. ph = -log(10)(h+)

mass of one mole of ions = mass x avogardo constant