Which sample equation best illustrates the Law of Conservation of Mass? A. 12 grams reactant X + 10 grams reactant Y → 2 grams product Z + 7 grams product K
B. 5 grams reactant E + 5 grams reactant F → 20 grams product G + 5 grams product H
C . 10 grams reactant Q + 9 grams reactant R → 90 grams product S + 90 grams product
D . 20 grams reactant U + 3 grams reactant V → 23 grams product W

D . 20 grams reactant U + 3 grams reactant V → 23 grams product W

Explanation:

Law of conservation of mass states:

The mass of a closed system (As a reaction), is neither created or destroyed.

That is, the mass of reactants is equal to mass of products.

A. In reaction A 22g of reactants produce 9g of products. This reaction doesn't illustrates the law of conservation of mass.

B. 10g reactant produce 25g of products. This reaction doesn't illustrates the law of conservation of mass.

C. 19g of reactants produce 180g of products. This reaction doesn't illustrates the law of conservation of mass.

D. 23g of reactants produce 23g of products. -This is the reaction that best illustrates the Law of Conservation of Mass.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%

the correct answer is:

a. formation of precipitation