what is the molarity of the solute in the following solution: a 12.5% w/v Co(NO3)2 solution?

12.5% w/v means 12.5 g Co(NO3)2 in 100 mL solution.

Convert 12.5 g Co(NO3)2 to moles. The M = moles/0.100 = ??

i did that i just added the molecular wieght up wrong. thanks for making me recheck the working.

To determine the molarity of a solute in a solution, you need to know the amount of solute in moles (mol) and the volume of the solution in liters (L). In this case, you have a 12.5% w/v (weight/volume) solution of Co(NO3)2.

Step 1: Convert the percentage to grams per 100 mL
Since it is a 12.5% w/v solution, it means there are 12.5 grams of Co(NO3)2 dissolved in 100 mL of the solution.

Step 2: Convert the volume to liters
To calculate the molarity, we need the volume of the solution in liters. Since 1 L is equivalent to 1000 mL, we have 100 mL / 1000 mL/L = 0.1 L.

Step 3: Calculate the moles of Co(NO3)2
To find the moles of Co(NO3)2, we need to know its molar mass. The molar mass of Co(NO3)2 can be calculated as follows:
Co: 1 atom * atomic mass of Co
N: 2 atoms * atomic mass of N
O: 6 atoms * atomic mass of O

The atomic mass of Co = 58.93 g/mol, N = 14.01 g/mol, and O = 16.00 g/mol.
So, the molar mass of Co(NO3)2 = (1 * 58.93) + (2 * 14.01) + (6 * 16.00) = 291.11 g/mol.

Step 4: Calculate the moles of Co(NO3)2
Using the equation: moles = mass/molar mass
moles of Co(NO3)2 = (12.5 g / 100 mL) / 291.11 g/mol
= 0.043 mol

Step 5: Calculate the molarity
The molarity is the number of moles of solute per liter of solution.
Molarity (M) = moles/volume in liters
Molarity of Co(NO3)2 = 0.043 mol / 0.1 L
= 0.43 M

Therefore, the molarity of the Co(NO3)2 solute in the 12.5% w/v solution is 0.43 M.