Final answer:
To find the percentage by mass of sodium chloride in the solution, calculate the mass of sodium chloride and divide it by the mass of the entire solution. The percentage by mass of sodium chloride in the solution is approximately 2.17%.
Step-by-step explanation:
To find the percentage by mass of sodium chloride in the solution, we need to calculate the mass of sodium chloride and then divide it by the mass of the entire solution.
First, let's calculate the mass of sodium chloride in the solution.
The mass of the evaporating dish and its contents after evaporation is 56.7 g.
The mass of the empty evaporating dish is 54.3 g.
Therefore, the mass of sodium chloride is (56.7 g - 54.3 g) = 2.4 g.
Next, let's calculate the mass of the entire solution.
The mass of the sample of saline solution is 165.0 g.
Therefore, the mass of the entire solution is (165.0 g - 54.3 g) = 110.7 g.
Finally, let's calculate the percentage by mass of sodium chloride in the solution.
The percentage by mass is (mass of sodium chloride / mass of entire solution) × 100%.
Therefore, the percentage by mass of sodium chloride in the solution is (2.4 g / 110.7 g) × 100% ≈ 2.17%.