A 25.0 mL sample of HCI reacted with 20.0 mL of 2.00 M NaOH. What is the molarity of the HCI? HCl(aq) + NaOH(aq) —> NaCl(aq) + H2O(l)
really need help!

Molarity of HCl = 1.6M

Explanation:

The chemical reaction equation is;

HCl(aq) + NaOH(aq) —> NaCl(aq) + H2O(l)

Now, molarity = number of moles/volume

Thus, for NaOH, we have;

Number of moles = molarity × volume = 2M × (20/1000) L

Number of moles = 0.04 moles

Using the coefficients in the chemical equation above, we can find the corresponding number of moles for HCl.

Number of moles of HCl = 0.04 moles NaOH × (1 mole of HCl/1 mole of HCl) = 0.04 moles of HCl

Thus;

Molarity of HCl = 0.04/(25/1000)

Molarity of HCl = 1.6M

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)