Answer:
An unknow sample has 45.9 % sand and 54.1% salt.
Explanation:
Step 1: Given data
An unknown mixture of salt and sand weighs 7.52 g before washing with water;
After washing with water, this mixture weighs 3.45g
Step 2: Calculate mass of sand
The difference between the mass before and after washing, gives the amount of salt in the mixture. This because salt (NaCl) is soluble in water, but sand is insoluble. As final result, leaving only the sand behind.
⇒7.52 - 3.45 = 4.07g
Step 3: Calculate percentage of sand
To find the percentage of sand that was mixed with salt =
Dividing the mass of sand by the total mass of the mixture=
(3.45 g sand / 7.52g of mixture) X 100 = 45.9% sand
Step 4: Calculate percentage of salt:
If there is 45.9 % sand, this means there is 100% - 45.9 = 54.1% salt.
We can control this by dividing the calculated mass of salt (4.07g) by the total mass of the mixture =
(4.07 g of salt / 7.52g of mixture) X 100 = 54.1% salt
An unknow sample has 45.9 % sand and 54.1% salt.
