To 112 g of a 20% alkali solution of potassium hydroxide was added 30 g of water.
| July 17, 2021 | education
To 112 g of a 20% alkali solution of potassium hydroxide was added 30 g of water. Determine the mass fraction of the substance in the new solution.
Given:
m rast. = 112 g
v KOH = 20%
m water = 30g
To find:
v 1 KOH -?
Decision:
v = (mst .. / mst.) * 100%
m thing. = v * mst. / 100%
m KOH = 20% * 112g / 100%
m KOH = 22.4 g mass of potassium hydroxide in the initial solution.
m 1 plant. = 112g + 30g
m 1 plant. = 142g the mass of the solution after adding water.
The mass of KOH in the new solution remained the same (22.4 g)
v 1 KOH = 22.4g * 100% / 142g
v 1 KOH = 15.8% – mass fraction of KOH in the new solution.
Answer: 15.8% mass fraction of potassium hydroxide in the new solution.
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