Show Work for any of these
1.What is the molarity of a solution made with 25.2 g CaO in a total of 2 L of solution? Show your work, using dimensional analysis, being sure to use units throughout.

2.Calculate the molarity of the solution formed when 0.72 moles of CaBr2 is dissolved in 1.50 L water. Show your work

3.Find the molar mass of magnesium phosphate tribasic, which has a formula of Mg3(PO4)2

1. 0.224 M is the molarity of the solution made with 25.2 grams CaO in 2 litres of solution.

2. 0.48 M is the molarity of the solution formed when 0.72 moles of CaBr2 is dissolved in 1.50 L water.

3. 262.84 gm/mole is the molar mass of Mg3(PO4)2.

Explanation:

1. Data given:

weight of the mass of CaO = 25.2 grams

Atomic weight of one mole of CaO = 56.07 gram/mole

number of moles = mass÷atomic mass of one mole of the substance

                               =   25.2 ÷ 56.07

                               = 0.449 moles of CaO is used to make a solution of 2 Litres

formula for molarity:

molarity = number of moles ÷ volume in litres

               = 0.449 ÷ 2

                 = 0.224 M

2. Data given:

number of moles of CaBr2 = 0.72 moles

volume of the water used = 1.50 L

Formula of molarity:

molarity = number of moles ÷ volume in litres

molarity = 0.72 ÷ 1.5

               = 0.48 M

3. Molar mass of a compound is calculated by adding the number of moles of elements taking part in the formation of the compound.

Mg = 24.30 gm/mole

P = 30.97 gm/mole

O = 16 gm/mole

3 moles of Mg ( 24.3 x 3) + 2 moles of P (2 x 30.97) + 8 moles of O (8 x 16)

= 262.84 gm/mole is the atomic weight of Mg3(PO4)2

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