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Question
The conductivity of sodium chloride at 298 K has been determined at different concentrations and the results are given below:
| Concentration/M | 0.001 | 0.010 | 0.020 | 0.050 | 0.100 |
| 102 × κ/S m−1 | 1.237 | 11.85 | 23.15 | 55.53 | 106.74 |
Calculate ∧m for all concentrations and draw a plot between ∧m and c1/2. Find the value of `Lambda_m^0`.
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Solution
| Concentration (M) | C1/2 (M1/2) |
κ(S m−1) | κ(S cm−1) | Λm = `bb((kappa xx 1000)/M)` (S cm2 mol−1) |
| 0.001 | 0.032 | 1.237 × 10−2 | 1.237 × 10−4 |
`(1.237 xx 10^-4 xx 1000)/0.001` = 123.7 |
| 0.010 | 0.100 | 11.85 × 10−2 | 11.85 × 10−4 | `(11.85 xx 10^-4 xx 1000)/(0.010)` = 118.5 |
| 0.020 | 0.141 | 23.15 × 10−2 | 23.15 × 10−4 | `(23.15 xx 10^-4 xx 1000)/0.020` = 115.8 |
| 0.050 | 0.224 | 55.53 × 10−2 | 55.53 × 10−4 | `(55.53 xx 10^-4 xx 1000)/(0.050)` = 111.1 |
| 0.100 | 0.316 | 106.74 × 10−2 | 106.74 × 10−4 | `(106.74 xx 10^-4 xx 1000)/(0.100)` = 106.7 |
When the straight line is drawn backwards, it meets the ∧m axis at 124.0 S cm2 mol−1, which is the value of `Lambda_m^0`.
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