What volume of a 0.716 M KBr solution is needed to provide 10.5 g of KBr? a. 7.5

Question

What volume of a 0.716 M KBr solution is needed to provide 10.5 g of KBr? a. 7.52 mL b. 63.2 mL c. 811 mL d. 123 mL e. None of these Calculate the molarity, molarity and mole fraction of methanol (CH_3OH) in a composed of 26.5 g of CH_3OH and 244 g of water. (Assume that the density of the solution is 0.975 g/mL.) a) 2.98 times 10^3, 3.06, 0.0611 b) 2.98, 3.39, 0.0575 c) 298, 3.39, 0.0611 d) 2.98, 3.06, 0.0575 e) 2.98, 3.06, 0.0611 Determine the acid dissociation constant for a 0.010 M nitrous acid solution that pH of 2.70. Nitrous acid I a weak monotonic acid and the equilibrium equation of interest is HNO_2 (aq) + H_2O(I) doubleheadarrow H_3O^+(daq) d+ NOD_DD2(aq) a. 8.0 times 10^-3 b. 2.0 times 10^-3 c. 5.0 times 10^-4 d. 4.0 times 10^-4 e. None of these

Explanation / Answer

1.

find the no of moles of KBr

moles of KBr = weight KBr / molar mass of KBr

moles = 10.5 g / 119 g/mol

moles of KBr = 0.08823 mol

now use the formula

molarity M = moles / volume in Liters

volume in liters = moles / Molarity

volume in liters = 0.08823 mol / 0.716 M

= 0.123 L convert in to mL by multiplying with 1000

= 123 mL

option d is the correct answer

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