- Messages
- 179
- Reaction score
- 161
- Points
- 53
http://papers.gceguide.com/A Levels/Chemistry (9701)/9701_s16_qp_11.pdf
Q4 I dont understand what Np Pu means??
Q6 ??
Q17 ??
Q30??
http://papers.gceguide.com/A Levels/Chemistry (9701)/9701_s16_qp_13.pdf
Q9 ???
Q21 ??
Q33 Statement 2 ; No particles have zero energy at either temperature. ?? What does this mean in context?
Q17: You have to mentally or physically make a note of the equation of hydrochloric acid and calcium carbonate.
2HCl + CaCO3 = CaCl2 + CO2 + H2O
In this question, 36/1000 x 0.5 = 0.018 moles of HCl reacted with CaCO3.
As per equation, 2 moles of HCl reacted with 1 mole of CaCO3. How many moles of CaCO3 react with 0.018 moles of HCl then? That turns out to be, 0.018/2 = 0.009 moles of CaCO3. How much is the mass of 0.009 moles of CaCO3? Moles = mass/Mr. So, 0.009 = mass/Mr of CaCo3 = mass/100. Mass = 100 x 0.009 = 0.9 grams. This rock contains 0.9 g of calcium carbonate, and itself the entire thing weights 2 grams. So % of CaCO3 = 0.9/2 x 100 = 45%. Answer should be B.