1 Add an appropriate amount of 10% dilute hydrochloric acid to the mixture of 2 1.4g sodium carbonate and sodium chloride, and the gas is just 4.4g after complete reaction. Q:

1. How many grams of sodium carbonate does this mixture contain?

2. What is the mass fraction of the solution obtained after the reaction?

3. How much water needs to be evaporated to make the obtained solution saturated at 20℃? (Solute solubility at 20℃ is 36 g)

Answer 1. Only sodium carbonate reacts with dilute hydrochloric acid in the mixture, and the gas is carbon dioxide, so there is 0. 1mol of sodium carbonate, that is,10.6g..

2. Sodium carbonate is 10.6g, so sodium chloride is10.8g. The mass of sodium chloride generated after sodium carbonate reaction is 1 1.7g, so the total mass of sodium chloride in the solution is 22.5g The mass of dilute hydrochloric acid can be obtained indirectly from the first equation just listed: the mass of hydrochloric acid is 7./.

So what is the mass fraction of the solution? You should have forgotten, right? ....

3. The mass of water in the solution is 71g-7.1g = 63.9g..

Then 36/ 100=22.5/x to calculate the value of x, and then use 63.9-X, which is the mass of water to be evaporated.

Answer over. The idea of solving the problem is roughly like this. You'd better do the numerical calculation yourself, because I'm in class now, and I do it with my heart, so the correct rate may not be too high. )

Chemical problem solving method: step by step, not too fast!

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