Respuesta :
Answer is: 4.79 grams og KBr are required.
V(KBr) = 350 mL ÷ 1000 mL/L.
V(KBr) = 0.350 L; volume of potassium bromide solution.
c(KBr) = 0.115 M; molarity of potassium bromide solution.
n(KBr) = c(KBr) · V(KBr).
n(KBr) = 0.115 mol/L · 0.350 L.
n(KBr) = 0.04025 mol, amount of substance.
m(KBr) = n(KBr) · M(KBr).
m(KBr) = 0.04025 mol · 119 g/mol.
m(KBr) = 4.79 g; mass of potassium bromide.
M - molar mass.
4.79 grams of KBr are required to make 350 mL of a 0.115M KBr solution.
HOW TO CALCULATE MOLARITY?
The molarity of a solution can be calculated by using the following expression:
Molarity = no. of moles ÷ volume
According to this question, 350mL of a 0.115M KBr solution was given. The number of moles can be calculated as follows:
no. of moles = 0.350 × 0.115
no. of moles = 0.0403mol
Molar mass of KBr = 39 + 80 = 119g/mol
mass of KBr = 119g/mol × 0.0403mol
mass of KBr = 4.79g
Therefore, 4.79 grams of KBr are required to make 350 mL of a 0.115M KBr solution.
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