Answer:5.3 grams AgNO3
Explanation:
To solve your problem, take a look at the definition of molality (m):
moles of solute/kg of solvent
You are given the grams of solvent (water) to find the grams of silver nitrate.
First, convert 250 grams to kg:
250 g * 1 kg / 1000g = 0.250 kg
Now that you have the kg of solvent, you can solve for the moles of solute:
kg of solvent * molality = moles of solute
0.250 kg * 0.125 m = 0.03125 mol AgNO3
You can convert the number of moles to grams using the molar mass of AgNO3, which is 169.872 g/mol:
moles of solute * molar mass of solute = grams of solute
0.03125 mol AgNO3 * 169.872 g/mol = 5.3085 g
Because your question provides two significant digits, you must round this number to get the final answer:
5.3 grams AgNO3
I hope this helps!