We wish to determine the mass of Mg required to react completely with 250 mL of 1.0 M HCl.

HCl reacts with Mg according to the equation below:
[tex]\[ 2 \text{HCl} (aq) + \text{Mg} (s) \rightarrow \text{MgCl}_2 (aq) + \text{H}_2 (g) \][/tex]

How many moles of HCl are present in 250 mL of 1.0 M HCl?



Answer :

To determine how many moles of HCl are present in 250 mL of 1.0 M HCl, we can follow these steps:

1. Convert the volume from milliliters to liters:

We know that there are 1000 milliliters in a liter. Therefore, we need to convert 250 milliliters (mL) to liters (L).

[tex]\[ \text{Volume in liters} = \frac{250 \text{ mL}}{1000} = 0.25 \text{ L} \][/tex]

2. Use the molarity to determine the moles of HCl:

Molarity (M) is defined as the number of moles of solute (in this case, HCl) per liter of solution. Given that the concentration of HCl is 1.0 M, we can calculate the moles of HCl using the formula:

[tex]\[ \text{Moles of HCl} = \text{Molarity} \times \text{Volume in liters} \][/tex]

Substituting the given values:

[tex]\[ \text{Moles of HCl} = 1.0 \text{ M} \times 0.25 \text{ L} = 0.25 \text{ moles} \][/tex]

So, there are 0.25 moles of HCl present in 250 mL of 1.0 M HCl.