I need help plugging these in. I didn’t understand what DrBoB222 meant
2.A student starts with a titration by placing 30.0mL of 0.25M NaOH into a flask with 3 drops of phenolphthalein. The student then titrated to the endpoint using 18.0mL of HCI. Calculator concentration (molarity) of the HCI that the student used NaOH + HCl ==> NaCl + H2O mols NaOH = M x L = ? The equation is 1 mol HCl to 1 mol NaOH; therefore, mols HCl = mols NaOH Then M HCl = mols HCl/L HCl = ?
For finding an unknown molarity of a substance in a titration, we use the following formula:
(M1 * V1) / (M2 * V2) = (n1 / n2)
Where,
M1 = Molarity of chemical 1
M2 = Molarity of chemical 2
V1 = Volume of chemical 1
V2 = Volume of chemical 2
n1 = Stoichiometric coefficient in the reaction of chemical 1
n2 = Stoichiometric coefficient in the reaction of chemical 2
You've been given M1, V1, and V2. Dr.Bob showed you, with the reaction, that n1 = n2 = 1. Now, you're left with just one variable, M2. Can you find the required Molarity?
To calculate the concentration (molarity) of the HCl used by the student, we need to follow a step-by-step approach:
Step 1: Calculate the number of moles of NaOH used.
mols NaOH = Molarity (M) x Volume (L)
Given: M NaOH = 0.25M and V NaOH = 30.0 mL (convert to L by dividing by 1000)
mols NaOH = 0.25M x 0.0300L = 0.0075 mol
Step 2: Determine the number of moles of HCl used.
According to the balanced equation, the ratio of NaOH to HCl is 1 mol:1 mol. Therefore, the number of moles of HCl used is equal to the number of moles of NaOH.
mols HCl = mols NaOH = 0.0075 mol
Step 3: Calculate the concentration (molarity) of HCl.
Molarity (M) = moles/Liters
Given: V HCl = 18.0 mL (convert to L by dividing by 1000)
M HCl = 0.0075 mol / 0.0180 L = 0.4167 M
Therefore, the concentration (molarity) of the HCl used by the student is 0.4167 M.