Calculate the molarity of a solution if 300.0 mL of it contains 16.8 g of KNO3.
[Use formula weight: KNO3, 101.11 amu]....Question do I need to convert 300.0 mL to L? My initial set up looks like this: (16.8g/101.11amu)/300.0 mL my answer turns out to be 0.000553852....however the correct answer is 0.533M...thanks a billion!
Okay I think i figured it out...the answer given for this problem: 0.533M is incorrect! The right answer is: 0.553M b/c u do have to convert 300 mL into L. so problem looks like this: (16.8g/101.11)/0.3L
Your second post is correct. The definition of molarity is M = moles/L. That's why the 300 mL must be converted to 0.300 L.
Yes, you need to convert the volume from mL to L because the molarity (M) is defined as moles of solute per liter of solution.
To convert 300.0 mL to L, simply divide by 1000:
300.0 mL ÷ 1000 = 0.300 L
Now, let's calculate the number of moles of KNO3:
moles of KNO3 = mass of KNO3 / formula weight of KNO3
moles of KNO3 = 16.8 g / 101.11 g/mol = 0.166 moles
Finally, we can calculate the molarity:
Molarity = moles of KNO3 / volume of solution (in liters)
Molarity = 0.166 moles / 0.300 L
Molarity ≈ 0.553 M (rounded to three decimal places)
The correct answer should be 0.553 M, not 0.533 M.
To calculate the molarity of a solution, you need to express the amount of solute in moles and the volume of the solution in liters. In this case, you are given the mass of the solute (16.8 g) and the volume of the solution (300.0 mL).
Yes, you need to convert the volume from milliliters (mL) to liters (L) because molarity is defined as the number of moles of solute per liter of solution.
To convert 300.0 mL to L, you can use the conversion factor 1 L = 1000 mL:
300.0 mL × (1 L / 1000 mL) = 0.300 L
Now, let's calculate the number of moles of KNO3:
moles = mass / molar mass
moles = 16.8 g / 101.11 g/mol ≈ 0.166 moles
Finally, you can calculate the molarity:
Molarity = moles / volume in liters
Molarity = 0.166 moles / 0.300 L ≈ 0.553 M
It seems that you made a calculation error when dividing the moles by the volume. The correct answer should be approximately 0.553 M, not 0.000553852.