SSCE HSC Chemistry Using Quantitative Analysis: Four students analysed a sample

Question

Four students analysed a sample of fertiliser to determine its percentage of sulfate.

Each student:

- weighed an amount of fertiliser;
- dissolved this amount in 100 mL of water;
- added aqueous barium nitrate;
- filtered, dried and weighed the barium sulfate precipitate.

Their results and calculations are shown in the table.

| Student | Mass of fertiliser used (g) | Mass of BaSO₄ weighed (g) | Percentage of sulfate in fertiliser (%) |
| ------- | ----------------------------- | --------------------------- | ----------------------------------------- |
| A       | 11.6                          | 19.5                       | 69.2                                    |
| B       | 10.4                          | 16.9                       | 66.9                                    |
| C       | 10.268                        | 22.612                     | 69.9                                    |
| D       | 11.1                          | 18.2                       | 67.5                                    |

The percentage of sulfate calculated by Student C was significantly higher than that of the other students. Which is the most likely reason for this?

(A) Student C did not dry the sample for long enough.

(B) Student C added more Ba(NO₃)₂ than the other students.

(C) Student C used a balance capable of measuring weight to more decimal places.

(D) Student C waited longer than the other students for the Ba(NO₃)₂ to react completely with the sulfate.

Four students analysed a sample of fertiliser to determine its percentage of sulfate - HSC - SSCE Chemistry - Question 13 - 2001 - Paper 1

Worked Solution & Example Answer:Four students analysed a sample of fertiliser to determine its percentage of sulfate - HSC - SSCE Chemistry - Question 13 - 2001 - Paper 1

Which is the most likely reason for this?

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