What mass of solute is contained in 256ml of a 0.875 m ammonium chloride solution?

 Number of moles = 0.256*0.895 as M = moles/liter so 0.229 moles.

And NH4Cl has mol. wt. of 14+4*1+35.5 = 53.5 g/mole.

So 53.5*0.229 g = 12.3 g

m = 11.97 g

Explanation:

First, the ammonium chloride has the formula NH₄Cl. This molecule, has the elements N (MW = 14 g/mol), H (MW = 1 g/mol) and Cl (MW = 35.45 g/mol).

To get the mass of solute, we need to use the following the expression:

m = n * MM

So, in order to get the mass, we need to moles of the solute. This can be obtained with the molarity of the solution:

M = n/V > solving for n:

n = M*V

We have the volume (Which is in mL, so, we need to pass it to Liters dividing by 1000) and the molarity so, the moles of the solution are:

n = 0.875 * (256/1000)

n = 0.224 moles

We have the moles, now we calculate the molar mass of the solute:

MM = 14 + (4*1) + 35.45

MM = 53.45 g/mol

Finally the mass of the solute:

m = 0.224 * 53.45

the answer is d.) potassium