Question

A solution of barium hydroxide Ba(OH) contains 4.285 g of barium hydroxide in 100.0 mL of solution. What is molarity of the solution

Answer 1

The correct answer is 0.28 M

Step-by-step explanation:

First we have to calculate the molecular weight (MM) of BaOH:

MM(BaOH) = 137.3 g/mol + 16 g/mol + 1 g/mol= 154.3 g/mol

The number of moles of BaOH there is in the solution is obtained from the mass (m) divided into the molecular weight:

moles of BaOH = m/MM(BaOH) = 4.285 g/154.3 g/mol = 0.028 moles

The molarity of the solution is the number of moles of BaOH in 1 liter of solution. So, we divide the moles into the volume and then we have to convert ml to L (1000 ml = 1 L). For this, we multiply by the conversion factor 1000 ml/1 L, as follows:

M = 0.028 moles/100.0 ml x 1000 ml/1 L = 0.28 mol/L = 0.28 M ≅ 0.3 M

Answer 2

`M=0.25M`

Step-by-step explanation:

Hello,

In this case, molarity is defined as the relationship between the moles of the solute (barium hydroxide) and the volume of the solution in liters:

`M=(n_(Ba(OH)_2))/(V_(sln))`

In this case, as the barium hydroxide molar mass is 171.34 g/mol, one obtains the molarity in molar units (M=mol/L) as:

`M=(4.285gBa(OH)_2*(1molBa(OH)_2)/(171.34gBa(OH)_2) )/(100.00mL*(1L)/(1000mL))\\\\M=0.25M`

Best regards.