Notes: All questions are based on the data provided in Table I.
Although spreadsheets may be used, one example Of each calculation is required for full marks.
Remember to state all assumptions.
Questions:
4.
Express the composition Of both samples in:
a) millimolarity (2 marks)
b) millimolality (2 marks)
c) ppm (2 mark s)
d) meq L - ' (2 marks)
Convert porp to POa3- and P in mg L -1. (4 marks)
Convert alkalinity into HCO'- concentrations in mg (2 marks)
Calculate TDS in mg l:' for both samples. (2 marks)
Is the charge imbalance (i. e„ charge balance error) a measure of accuracy or precision? What is the
difference between these two measures of error? (4 marks)
Calculate the charge balance error for both samples. Is there any evidence either analysis may have
analytical errors? (4 marks)
Apart from analytical error, suggest two specific factors that may lead to a charge imbalance of greater
than 5%. (4 marks)
Table l. Chemical analysis results for two Water samples.
parameter
pH
Alkalinity
soe-
poa. p
Density
units
mg L•' (as cacoo
mg L-'
mg L"'
mg L"'
mg L"
mg
mg L-t
mg
Value
Sample A
340
1.4
14
6.7
140
31
44
0.28
1.000
Sample B
32
2700
4500
9800
16
0.12
1.012