Calculate the concentrations of the following solutions, assuming the volumes are exact measurements:
a. 18.64g of sodium hydroxide in 350mL of solution
b. 8.97mL of 18M hydrochloric acid in 250mL of solution
A. Concns come in many flavors such as molarity, molality, normality, percent by mass, percent by volume, etc. M is what follows for my response. moles = grams/molar mass. Solve for moles. Then M = moles/L
B.18M x (8.97mL/250 mL)= ?
To calculate the concentrations of the given solutions, we need to determine the amount of solute (in moles) and the volume of the solution (in liters). We can then divide the amount of solute by the volume to get the concentration expressed in moles per liter, also known as molarity (M).
Let's calculate the concentrations for both solutions:
a) 18.64g of sodium hydroxide in 350mL of solution:
First, convert the volume from milliliters to liters:
350 mL = 350/1000 = 0.35 L
To determine the moles of sodium hydroxide, we need to use its molar mass. The molar mass of sodium hydroxide (NaOH) is the sum of the atomic masses of sodium (Na), oxygen (O), and hydrogen (H), which is:
Na: 22.99 g/mol
O: 16 g/mol
H: 1.01 g/mol
Molar mass of NaOH = 22.99 + 16 + 1.01 = 40 g/mol
Now, we can calculate the moles of sodium hydroxide:
moles = mass / molar mass
moles = 18.64 g / 40 g/mol = 0.466 mol
Finally, divide the number of moles by the volume in liters:
concentration = moles / volume
concentration = 0.466 mol / 0.35 L ≈ 1.331 M
Therefore, the concentration of the sodium hydroxide solution is approximately 1.331 M.
b) 8.97 mL of 18M hydrochloric acid in 250 mL of solution:
First, convert the volumes to liters:
8.97 mL = 8.97/1000 = 0.00897 L
250 mL = 250/1000 = 0.25 L
Since the given hydrochloric acid solution is already in molarity (M), the concentration is directly provided.
Therefore, the concentration of the hydrochloric acid solution is 18 M.