Higher June 2019 Paper 3 Q13
13 The density of ethanol is 1.09 g/cm3
The density of propylene is 0.97 g/cm3
60 litres of ethanol are mixed with 128 litres of propylene to make 188 litres of antifreeze.
Work out the density of the antifreeze.
Give your answer correct to 2 decimal places. (4)
| Answer | Mark | Mark scheme |
|---|---|---|
| 1.01 | P1 | for \(1.09 \times 60\) (= 65.4 or \(\dfrac{327}{5}\)) or \(0.97 \times 128\) (= 124.16 or \(\dfrac{3104}{25}\)) |
| P1 | for \(1.09 \times 60\) (= 65.4 or \(\dfrac{327}{5}\)) and \(0.97 \times 128\) (= 124.16 or \(\dfrac{3104}{25}\)) or \(\text{``}65.4\text{''} + \text{``}124.16\text{''}\) (= 189.56 or \(\dfrac{4739}{25}\)) | |
| P1 | for a complete process to find the density of antifreeze eg \((\text{``}65.4\text{''} + \text{``}124.16\text{''}) \div 188\) or \(189.56 \div 188\) or \(\dfrac{4739}{25} \div 188\) | |
| A1 | for answer in the range 1.00 to 1.01 |
Additional guidance
Note that the volumes may be converted to ml, eg \(1.09 \times 60000\ (= 65400)\)
Candidates working in ml must use 188,000
If an answer within the range is seen in working but then rounded incorrectly award full marks.
Accept 1 for 1.00
Note that the correct value is 1.008.....