National Chemistry

1998 Credit Hints

Credit 1998 First thoughts
   hints
  answers

1998 CREDIT Hints

1. (a) Protons + neutrons - probably nothing to do with electrons then.
(b) Look at page 1 of data book -electron arrangements

2.(a) Reduction is on page 7 RIG
(b) Should make an acid (H+)
(c) Both should have an acid (H+) at the start.
Unlikely that any box is used twice.

3. Write out the molecular formulae of each box -
CH2O2; C2H6O; C2H4O; C2H6O; C3H8O
(a) Look at the molecular formula you have written
(b) Look at the molecular formula you have written - only 1 oxygen

4. Remember OP and HI for Haber and Oswald process
(a) Where are enzymes found?
(b) TWO answers. Two of them start with hydrogen (H2)

5. (a) NOT making faster - more particles the faster it is.
(b) TWO ways to get more product.
Needs increase in chemicals to make more.

6.(a) glucose ---> starch (big molecule)
(b) TWO reaction - look at the equation involved.
Unlikely that any box is used twice.
Try and get rid of wrong answers.

7.TWO answers - corrosion so page 7 may help.
A. Above or below iron to give protection?
B. Fe is correct test; is result correct
C. Does plating make a barrier? Are these the correct things to be protected from?
D. Above or below iron to give protection?
E. is it the -ve or the +ve that protects ?

8. TWO answers.
Treat each statement as true/false
A. Does octane ignite before 0 ?
B. Find two isomers and compare. It is a definition you need to know.
C. Read down the last two columns.
D. Find hydrocarbons in the same series and compare.

part 2

9(a) Definition you should know. Look at the example for clues.
(b) It is an ion - so be careful about umber of electrons
(c) think about the photosynthesis equation.
water + carbon dioxide ----light and ........----> starch

10. (a) Use the words in the diagram -electrons and nucleus.
(b)(i) Get the electron arrangement of chlorine.
How does it become an ion?
(ii) Solid - high melting point. Strength.

11. (a) Spectators do not take part. remove from both sides.
(b) When drawing it make sure you draw a liquid in each beakers.
What else would go in the beakers. Connecting wires!

12. (a) Look at the diagram where the air goes in.
Which of the equations does this refer to?
(b) Compare the two in the equations - especially number 1.
(c) Fe2O3 + CO ---> Fe + CO2
  Fe

Leave oxygens to last as they appear in most places
(d) Percentage is actually total mass of 100g.
How much iron is there = 48.3 divided by mass of 1 mole.

13.(a)(i) What is this subject?
(ii) Disadvantage of a battery? Portable is an advantage
(b) Look at the equation. use page 7
Oxidation is OIL
(c) What is needed?

14. Looks complicated but it is not.
Just read carefully - mark the two examples on the graph.
TWO trends
What makes the difference between the first two columns?
Now compare each set of columns.

15. (a) temperature (along the way) increases what happens to solubility?
(b) So it is pH 1 and increases, gets lass acidic, when heated. Use the graph.
16.(a) SOD! reminds you of what?
(b) Test for ammonia. need to know. Something to do with pH!
(c) Ammonium "what" would react with barium chloride to make solid - page 5
You would get ammonium chloride and barium .......

17. READ from the top.
(a) What is in the flask? stage 1
(b) What makes this fast? stage 1
(c) Thermometer - why?
(d) look at boiling points - this may help with part (c)

18. (a) (i) You have two figures - calculate the third.
Concentration is mol/l (if you cannot calculate put 5)
(ii) 1 silver with 1 chloride. Use figure from part (i)
Part (i) told the silver therefore how much chloride ? (if you cannot calculate put 5)
(iii) use figure from part (ii). Mass mentioned so need mass 1 mole.
(b) Write down the ions - use page 4.

19. (a) Look at the structure. lots of reactions mentioned in Q6
(b) Sodium chloride must have something that ethylene glycol does not.
(c) Remove the oxygen from the water and from the right hand side

20. (a) Two or more metals - page 7.
Mark the metals on the activity series.
(b) see the pattern - not outrageous
(c) TWO ways - look at the diagram.
Temperature is changing.
(d) Think about what you could see! Bubbles, colour etc

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