The salt melt up to 38g in 100g of hot water of 80 degrees Celsius.
Answer the following questions.
(1) The salt 19g was put in 30g of hot water of 80℃ and it is mixed well.
Find the weight of the salt that remains without melting.
(2) The hot water of 80℃ is continuously added while mixing well.
How many grams of hot water was added when all salt melts?
Moreover, find the concentration of the salt solution.
Noted that the concentration should be rounded off the 2nd decimal place and should be found the 1st decimal place.
Answer
(1) 7.6 g
(2) Hot water 20 g, Concentration 27.5%
Solution
(1) 38 × 19/38 = 11.4g
19 - 11.4 = 7.6g
(2) 100 ×19.38 = 50g
50 -30 = 20g
19 / (50 + 19) = 19 / 69 = 0.2753----
Thus it is 27.5%.
