National Chemistry


2001 General
   Almost the answers

 1. (a) Tempting to use page 1 but page 4 answers it quicker.
(b) Kr number 36; Po is 84; K is 19; P is 15; Pt is 78; Pb is 82
remember to pick 2 boxes

(c) catalytic converter is used in cars - must be solid and unreactive
Do not use leaded petrol

2. Identify chemicals used to test for substances given in each question.
This should be three different answers.
Read all three questions and do in order you find easiest.
Look at the five chemicals all are used in tests try to identify what each tests for.
These last two instructions may help eliminate possible answers.
(a) Starch - a carbohydrate
(b) Glucose - another carbohydrate
(c) Unsaturated - C=C<

A. blue to orange (needs heat ) indicates what ?
B. decolourised by
C. turns blue in presence of ?
D. turns blue/black in presence of ?
E. goes milky with what ?

3. (a) Look at the spelling.
remember to pick 2 boxes
(b) You have "eth", "pent", "prop" and "hex as beginnings indicating the number of carbons. Since you need TWO then both "prop" or both "Pent" are only possibles.
(c) The more carbons the higher boiling point - check on page 6

4. (a) galvaniZ(n)e
(b) Page 4 of data book - look for yellow flame test
(c) Not elements ie not in Periodic table; not on paper
remember to pick 2 boxes

5. Six reactions you could recognise
A. changes pH
B. two substances add together to produce one
C. needs electricity
D. forms a solid
E. burning
F. one substance "kicks out" another

(a) C=C gives this away
(b) Acid reaction gives this away

6. Useful to know about gases.
Try and write the formula for each in the boxes to help.
A, CH4
B. NH3
D. CO2
E. N2
F. O2

(a) pH paper blue = alkaline gas - only one known to you
(b) Carbon and hydrogen only
(c) Taken in by plant during photosynthesis
(d) Must be gases present in the air
remember to pick 2 boxes

7. In this style of question then there are TWO correct answers and three wrong answers
- work through each statement individuaally deciding if it is True/ False.
Watch for statements that are the opposite of each other - both cannot be correct and one usually is.
each statement must be TRUE for both gold and silver

A. page 8 numbers 47 &amp; 79 &quot;are they NOT transition metals
B. both metals - TRUE
C. found as pure metals ?
D. page 7 - are these metals unreactive ? low down electrochemical series
E. page 7 - compare to copper are they above copper in electrochemical series

Part 2
8. (a) Draw on diagram position of electrons found in fluorine - page 1 gives electronic configuration of 2,7
(b) Charged particles found in atoms are positive protons and negative electrons.
Neutral means no charge

9. (a) (i) carbon dioxide is a non-metal oxide
sodium oxide is a metal oxide - group 1 metals are the alkali metals
pH is a number
(ii) Check page 5 of the data book - the solubility tables
(b) sodium + oxygen (diatomic) ------> sodium oxide

10. (a) The repeating unit is

3 monomer units would be 6 C joined together
(b) "thermo" for heat - "setting" or "plastic" for softened
(c) label both axes - actually given here as "%" and "use"
put on the scale along the way two large boxes for each use
up the way each large box worth 5;
make sure over half the graph paper is used;
plot points
make sure it is a bar graph.

11. (a) definition of a catalyst is a MUST KNOW
(b) When making a statement about a relationship given in a graph you can usually frame your answer as follows
"As the data along the way increases then the data up the way increases or decreases (pick one)
As the temperature increases then the % SO2converted increases or decreases (pick one)"
(c) It must be bad or dangerous!!!
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12. (a) Breaking down a compound using ELECTRicity.
(b) The negative electrode attracts what kind of ion?
(c) Copper chloride solution - copper at negative electrode so what at positive electrode ?
If you can SEE - colour change; solid formed; bubbles of gas etc.
(d) Suitable for ELECTRodes.

13. (a) Chemical name for rust ? = iron oxide
Gases in air ? = nitrogen and oxygen
One fifth is in bold.
(b) Larger piece of iron and same amount of air
(c) For the iron ION not compound.
Copy an iron ion from data book page 7

14. (a) (i) Haber or Ostwald
(ii) nitrogen dioxide + air + X go into absorber nitric acid appears
NO2 + O2 + X ----> HNO3
(b) Why was nitrogen chemistry so important ?

15. (a) (i) What is in the battery ?
What supplies the electrons ?
(ii) use your common sense.
(b) (i) Use page 7 to help electrons flow from more reactive to less reactiv
  Draw the arrow on or above the wire NOT on the potato.
(ii) Replacing a metal in a cell would increase or decrease the voltage
the bigger the gap between the metals on page 7 the higher or lower the voltage produced ?

16. (a) Volume at end of reaction at the longest time.
Make sure it is experiment A (it is not 22cm3 !!!)
(b) SAME volume and concentration must have something the SAME on the graph.
(c) Must be something different between A and B at the start of the graph.
(d) Speeds up a chemical reaction but is unaffected itself.

17. (a) Cracking or fractional distillation ?
(b) The bigger the molecules the higher the density &amp; melting point &amp; viscosity &amp;
ignition temperature &amp; boiling point &amp; darker the colour
(c) It is a comparison so do something to petrol and then the same to lubricating
The burette and beaker suggests a liquid is poured into the beaker.

18. (a)(i) eg Cl2
(ii) Ionic, covalent or metallic are the types of bonding?
(b) (i) When making a statement about a relationship given in a table you can usually frame your answer as follows "As the data in first column increases then the data in the second column increases or decreases (pick one)"
In this case
As the Atomic number increases then the boiling point increases or decreases (pick one)
(ii) Look at the figures and estimate the missing value make it sensible by looking at the other differences.

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