A student investigates the rate of reaction between marble chips (calcium carbonate) and dilute hydrochloric acid. The reaction is carried out in an open conical flask placed on a digital balance. The student records the total mass of the flask and its contents every 30 seconds.
| Time / s | 0 | 30 | 60 | 90 | 120 | 150 | 180 | 210 | 240 |
|---|---|---|---|---|---|---|---|---|---|
| Mass of flask and contents / g | 150.00 | 148.80 | 147.95 | 147.40 | 147.10 | 147.00 | 147.00 | 147.00 | 147.00 |
Explain the trends shown by the data in the table.