National Chemistry

2007 Credit Hints

2007 CREDIT Hints

1. (a) Need to know the gas tests. Get rid of wrong ones.
(b) Need to know the gas tests. Get rid of wrong ones.
Unlikely to be same answer for both questions.

2. (a) SLOWEST - using metal, temperature, particle size and concentration.
Which metal will be faster?
(b) Temperature can change rest must stay the same.

Temperature = 20oC temperature = 30oC temperature = 40oC
  A C E
Cannot be two from same column.
Now mark each metal beside each box

3. (a) Tar - solid or gas ? -
(b) Lowest must be one of the extremes - so A or E.

4. Write the molecular formulae in each box.
C3H6; C3H6; C4H10; C4H8; C3H6; C4H8
(a) Which is butene - number of carbons from page 6.
(b) TWO parts - general formula - double number of hydrogens - and not react with hydrogen.

5.(a) moLOWcules and conductivity of covalent compound
(b) Melts before 25oC and conductivity. of metallic element

6. (a) Must make an acid. (H+ ion)
(b) Acid (H+ ion) must be a reactant.
(c) TWO
What are oxidised (OIL) on page 7

7. Need to know about electrons, protons and neutrons.
TWO of these statements will be true. for both p.... proton and n.... netron

8. Reactants are acid and oxide.
TWO of these statements will be true
A. as acid reacts hydrogen ion increase? T/F
B. carbon dioxide from an oxide ? T/F
C. What is the salt ?
D. hydrogen gas from an oxide? T/F
E. water from and oxide ? T/F

Can C, D and E all be correct?

9. Metals - use page 7. Check diagram for which electrode is more reactive.
mark each pair of data book

part 2

10. (a) What are the masses of the isotopes? Which would there be most of?
(b) Watch, it is an ion. How many electrons in the atom? Cannot tell from data book page 1.
(c) (i) Copy out the equation and do working below it.
AgNO3 + Cu ----> Ag + Cu(NO3)2

Look at NO3-

(ii) Metals - page 7.

11. Write out molecular formula for each molecule. CH2O2; C2H4O2; C3H6O2
 (a) Given one, two and three carbons as an example.
(b) (i) Find number of carbons first.- page 6 helps
(ii) How many carbons in pentanoic acid? Prediction should make sense

12. (a) Label the axes (using words in table) and create axes so that over half of graph paper is used..
mark the points and join the dots
(b) Put mark on graph and read off.
(c) SOD ! What element does it remind you of?

13.. Looks complex but is straight forward.. Read example carefully.
In example HSt (hydrolysed starch) has one spot which is the same as ...?
(a) Looking for Hsu
(b) catalyst for sugars.. Digestive system is in your body.

14. (a) 50% chance.. Want steel (Fe) not to lose electrons.
(b) (i) Zzzinc (sounds like)
(ii) Two metals - page 7 of data book. Does not rust even when scratched.

15. (a) Match diagram to electron arrangement of chlorine.
HCl has one chlorine and one hydrogen.
(b) Again look at electron arrangement - stable.

16. Write out molecular formula of the molecules. C3H6; H2O; C3H8O; C3H8O
(a)(i) Use words and diagram to get a word equation.
(ii) Experiment is a little bit hotter.
(b) (i) Look at the reactants. What is special about propene structure.
(ii) You have never heard of these before so look at the formula.
(iii) Separating a mixture. such as air or hydrocarbons

17. (a) Look at the formula.
(b) Again look at the formula for gibbsite in the table.
(c) Mass - so find mass of 1 mole. What mass calcium in this?
(d) Write it in words first.
(e) Page 7 for metals.. needs a little bit of help (heat)

18. (a) 'Thermo' to do with heat.
(b) The equation and words tell you what was formed. Nylon and ....?

19. (a) Must be mentioned in table.
(b) Write down both ions.
(c) (i) What ions are present in copper(II) chromate?
(ii) 'Electro'lyte!
(iii) Ions causing a problem - try page 5

20. Circle the figures in the question.
(a) Using cm3 and mol/l find a third figure. (Guess 5 if you cannot work anything out)
(b) (i) If you have no answer from part (a) put the figure 5 in as an answer then use it.
Match it into the equation.
1 mole CaCO3 reacts with 2 moles HCl (if you cannot calculate anything put in 5)
(ii) If you have no answer from part (bi)) put the figure 5 in as an answer then use it.
Mass means that you usually need mass of 1 mole.

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