2.5 g of sodium chloride was dissolved in 250 g of water. Determine the mass fraction of salt in the resulting solution.

Given: m (water) = 250 g, m (salt) = 2.5 g.
Find: ω (salt) -?
1. Find the mass of the solution:
m (solution) = m (salt) + m (water) = 2.5 g + 250 g = 252.5 g.
2. Find the mass fraction of the dissolved substance (salt):
ω (salt) = m (salt) / m (solution) = 2.5 g: 252.5 g = 0.0099, or,
multiplying this value by 100%, we get 0.99%.
Answer: 0.99%.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.