Concentrations of sodium chloride solution. They peeled off the
outer papery leaves of the
ated the effect of soaking small onion bulbs in different
onion bulbs and divided the onions into 6 batches, each with 10 onions,
The onions were surface dried with paper towels and weighed. The mean mass of
the onions in each batch was calculated. The onions were then left in sodium chloride
solutions for three hours.
After three hours the students surface dried the onions and weighed them again. Their
results are given in Table 3.1.
concentration of
sodium chloride
solution/ g dm3
percentage change
in mass
0
25
Table 3.1
mean mass of onions/g
before after soaking
soaking for 3 hours
147
173
153
165
176
172
154
149
149
142
183
175
50
+17.7
+7.8
-2.3
-3.2
-4.7
100
150
200
(b) Students calculated the percentage change in mass of the onions that were in the
most concentrated solution of sodium chloride.
Explain why the students calculated the percentage change in mass of the onions,​