A student investigated the temperature change during the endothermic reaction between citric acid solution and solid sodium hydrogencarbonate (NaHCO3\text{NaHCO}_3NaHCO3) in a glass beaker.
The student added portions of 3.0 g3.0\text{ g}3.0 g of sodium hydrogencarbonate to 25 cm325\text{ cm}^325 cm3 of citric acid solution and recorded the temperature after each addition. The results are shown in the table below:
| Mass of NaHCO3\text{NaHCO}_3NaHCO3 added (g\text{g}g) | Temperature (∘C^\circ\text{C}∘C) |
|---|---|
| 3.0 | 18.2 |
| 6.0 | 16.8 |
| 9.0 | 15.4 |
| 12.0 | 14.0 |
| 15.0 | 12.6 |
| 18.0 | 11.2 |
The recorded temperatures follow a linear relationship.
Name a container the student could use instead of a glass beaker to minimize heat transfer with the surroundings and improve the accuracy of the results.
The starting temperature of the citric acid solution corresponds to the yyy-intercept of the line of best fit (where the mass of sodium hydrogencarbonate added is 0 g0\text{ g}0 g). Determine this starting temperature in ∘C^\circ\text{C}∘C.