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Paired Exercise 14.23 How many milliliters of 0.879 M H3PO4 will contain the fol

ID: 1045061 • Letter: P

Question

Paired Exercise 14.23 How many milliliters of 0.879 M H3PO4 will contain the following? rrect. Did you convert moles to volume by multiplying the number of moles by the inverse of the molarity? (a) 0.29 mol H3PO mL H3PO4 the tolerance is +/-296 Incorrect. Did you first convert grams to moles and then multiply moles by the inverse of the molarity to determine the volume? (b) 25.9 9 H3PO mL H3PO4 the tolerance is +/-2% Incorrect. Did you use Avogadro's number to convert the number of molecules into moles? (c) 5.65 x 1022 molecules of H3PO L H3PO4 the tolerance is +/-2%

Explanation / Answer

(a)

molarity = moles/volume

volume = volume in litres

moles of H3PO4 = 0.29 ( given in question )

molarity of H3PO4 = 0.879M ( given in question )

volume = 0.29/0.879

volume = 0.3299 Litres = 0.330 Litres

1 L = 1000 mL

0.330 L = 330 mL

volume = 330mL

( b )

moles = given mass / molecular mass

molecular mass of H3PO4 = 98 g/mol

given mass = 25.9g

mole = 25.9/98

mole = 0.264

again using the formula of molarity given above

volume = 0.264/0.879

volume =0.300 L = 300mL

(c)

no of molecules = moles * avagadros number

avagadros number = 6.023 * 1023

moles = no of molecules / avagadros number

moles = 5.65*1022 / 6.023*1023

moles = 0.094

molarity = moles / volume

volume = 0.094/0.879

volume = 0.107 L

volume 107mL