unit 1 - chemical changes and structure€¦ · focus on national 5 unit 1 culloden academy...

Focus on National 5

Unit 1 - Chemical Changes

and Structure

Name ____________________ Class ____________________

Focus On National 5 Unit 1

Culloden academy chemistry department 2

b mass number

b

Nuclide Notation

aX Number of protons = atomic number

Number of electrons = atomic number IF NEUTRAL atomic number + number of -ve charges IF NEGATIVE atomic number – number of +ve charges IF POSITIVE

Number of neutrons = mass number – atomic number

7 p = Li 3 e = n =

19 p = F 9 e = n =

39 p = Ca 20 e = n =

37 p = Cl 17 e = n =

235 p = U 92 e = n =

18 p = X e = n = 10

X is ________

56 p = Y e = n = 30

Y is ________

27 p = Z e = n = 14

Z is ________

7 p = Li+ 3 e = n =

19 p =

F-

9 e = n =

39 p = Ca2+ 20 e = n =

15 p = N3- 7 e = n =

235 p = U3+ 92 e = n =

31 p = X2- e = n = 15 X is

_________

9 p = Y2+ e = n = 5 Y is

_________

23 p = Z+ e = n = 12 Z is

_________

Symbol

atomic number



Writing formulae

yes

yes yes

no

no

no

element

Is it an element or

a compound?

Is it a diatomic

element?

Does it have a

prefix?

Write the symbol followed by a subscript

2 e.g. F2

Write the symbol on it’s own e.g.

Mg

Write the symbols with the prefixed element with the appropriate number e.g carbon dioxide

CO2

Write the formula using the symbols of the elements and the valency rules e.g. copper(II) oxide

CuO

Write the formula using the formula of the complex ion (s) from the data book, the symbol of the other element and the valency rules e.g.

sodium nitrate NaNO3

Does it contain a

complex ion?

compound

Valency rules

1. write down symbols

2. work out valencies

3. simplify if possible

4. cross over and write as subscripts to the right of the symbols (nb you

may need to use brackets with complex ions)

Group

number 1 2 3 4 5 6 7 0

Valency 1 2 3 4 3 2 1 0



For example: Magnesium chloride MgCl2 Bromine Br2 Aluminium sulphate Al2(SO4)3

Write the formulae for the following substances

1. nitrogen dioxide

2. potassium chloride

3. magnesium bromide

4. magnesium nitride

5. sulphur trioxide

6. copper (I) chloride

7. sodium phosphate

8. potassium hydroxide

9. ammonium chloride

10.lead (II) nitrate

11.uranium hexafluoride

12.nitrogen



Writing ionic formulae Ionic formulae can be written for:

IONIC compounds only Not for:

Covalent compounds Elements

Use prefix rules as before to write formula, but instead of using just symbol of the element, use the ionic symbol for simple ions or the ionic formula for complex ions. e.g. Mg2+ SO4

2- Na+ Cl- NH4+ O2-

If you need to write a subscript number to the right, you must use brackets e.g. (Mg2+)3 (SO4

2-)3 (Na+ 2 (Cl-)2 (NH4+)3 (O2-)3

Charges DO NOT simplify or cancel out. The total number of positive charges must equal the total number of negative charges. For example: Magnesium chloride Mg2+(Cl-)2 Aluminium sulphate (Al3+)2(SO4

2-)3



Write the ionic formulae for the following substances:

1. sodium phosphate


3. ammonium chloride

4. lead (II) nitrate

5. ammonium carbonate

6. caesium fluoride

7. lithium chloride

8. magnesium nitrate


10. ammonium bromide

11. rubidium fluoride

12. magnesium sulphate



Balancing equations

You can only balance equations by putting large numbers in front of

formulae – DO NOT change the formulae.

e.g. Mg(OH)2 + 2HNO3 Mg(NO3)2 + 2H2O

Balance these equations:

1. CO + O2 CO2 2. P + Cl2 PCl3 3. C + Br2 CBr4

4. C4H8 + O2 CO2 + H2O

5. H2O2 H2O + O2

6. Mg + AgNO3(aq) Mg(NO3)2(aq) + Ag

7. NaOH + H2SO4 Na2SO4 + H2O

8. AgNO3 + BaCl2 Ba(NO3)2 + AgCl

9. Na + H2O NaOH + H2 10. Al + Cl2 AlCl3

11. Fe + O2 FeO

12. Ca + H2O Ca(OH)2 + H2



Gram formula mass

Ca(NO3)2

1. Calculate the gram formula mass of calcium bromide, CaBr2

2. Calculate the gram formula mass of sodium oxide, Na2O

3. Calculate the gram formula mass of magnesium carbonate, MgCO3

4. Calculate the gram formula mass of ammonium nitrate, NH4NO3

5. Calculate the gram formula mass of aluminium nitrate, Al(NO3)3

6. Calculate the gram formula mass of ammonium phosphate, (NH4)3PO4

7. Calculate the gram formula mass of calcium hydroxide, Ca(OH)2

8. Calculate the gram formula mass of aluminium sulphate, Al2(SO4)3

6 x O = 6 x 16 = 96

2 x N = 2 x 14 = 28

1 x Ca = 1 x 40 = 40

= 164g



Calculations using the mole and gfm

1. Calculate the number of moles in 5.85g of NaCl. 2. Calculate the number of moles in 30g of SiO2. 3. Calculate the number of moles in 50g of (NH4)2SO4. 4. Calculate the number of moles in 340g of NH3.

m

gfm n

where: m = mass, in grams n = number of moles

gfm = gram formula mass



5. Calculate the mass of 5 moles of Na2SO4. 6. Calculate the mass of 0.1 moles of CaCO3. 7. Calculate the mass of 0.75 moles of CH4. 8. Calculate the mass of 2.5 moles of (NH4)3PO4.



Calculations using the mole and concentration

1. Calculate the number of moles in 500cm3 of 0.1 mol l-1 sodium chloride solution.

2. Calculate the number of moles in 3000 cm3 of 2 mol l-1 sulphuric acid. 3. Calculate the number of moles in 5 cm3 of 0.5 mol l-1 sodium hydroxide solution. 4. Calculate the number of moles in 200cm3 of a 4 mol l-1 lithium hydroxide solution. 5. Calculate the concentration of a 200cm3 solution containing 0.1 moles of a solid.

n

V c

where: n = number of moles c = concentration in mol l-1

V= volume in litres nb to convert cm3 into litres, divide by 1000



6. Calculate the concentration of a 50cm3 solution containing 0.05 moles of a solid. 7. Calculate the concentration of a 3000cm3 solution containing 2 moles of a solid. 8. Calculate the concentration of a 10cm3 solution containing 0.004 moles of a solid. 9. Calculate the volume of a solution containing 0.1 moles of a solid with a concentration of 0.5 mol l-1. 10. Calculate the volume of a solution containing 0.05 moles of a solid with a concentration of 1mol l-1. 11. Calculate the volume of a solution containing 2 moles of a solid with a concentration of 10 mol l-1. 12. Calculate the volume of a solution containing 0.4 moles of a solid with a concentration of 0.25 mol l-1.



Calculations using the mole, gfm and concentration

1. The gram formula mass of phosphoric acid is 98g.

If 49 g phosphoric acid is dissolved in water and the solution is made up to

200 cm3, what is the concentration of the resulting solution?

2. 52.5 g of pure citric acid (gfm 210 g) is dissolved in water and the solution is

made up to 500 cm3.

What is the concentration of the resulting solution?

m

gfm n

where: m = mass, in grams n = number of moles

gfm = gram formula mass

n

V c

where: n = number of moles c = concentration in mol l-1

V= volume in litres nb to convert cm3 into litres, divide by 1000



3. What mass of pure sodium nitrate is needed to make 1 litre of solution,

concentration 0.2 mol l-1?

4. The formula mass of sulphuric acid is 98 g.

What mass of pure sulphuric acid is required to make 100 cm3 of solution,

concentration 0.2 mol l-1?

5. What mass of sodium chloride, NaCl, is required to make 250 cm3 of a

solution with a concentration of 0.5 mol l-1?

6. What is the concentration of Mg(NO3)2 (aq) if 29.7g of solid is dissolved and

made up to 500 cm3?



Change in y-axis y2 – y1

Change in x-axis x2 – x1

Calculating rate of reaction from a graph

Rate = = e.g. Rate = Rate = Units are dependent on units of x and y axes e.g. g s-1, g min-1, cm3 s-1, l s-1

Change in mass

Change in time

Change in gas volume

Change in time



1.

Calculate the average rate of reaction, in g min-1, over the following times periods:

a) 0 – 200 minutes

b) 400 – 800 minutes

c) 600 – 1200 minutes

d) 0 – 2000 minutes

Mass / g

time / min



2.

Calculate the average rate of reaction, in cm3 s-1 over the following times periods: a) 0 – 5 seconds

b) 10 – 20 seconds

c) 10 – 40 seconds

d) 25 - 50 seconds

unit 1 - chemical changes and structure€¦ · focus on national 5 unit 1 culloden academy...

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