Magnesium metal reacts with hydrochloric acid to produce magnesium chloride plus hydrogen gas (H2) 6.
a) Write a balanced chemical equation for this process.
b) If 55 mg of magnesium are reacted with 18 mL of a 0.20 M HCl solution, what is the limiting reactant?
The Correct Answer and Explanation is :
(a) Balanced Chemical Equation:
[
\text{Mg} (s) + 2\text{HCl} (aq) \rightarrow \text{MgCl}_2 (aq) + \text{H}_2 (g)
]
(b) Identifying the Limiting Reactant:
To determine the limiting reactant, we need to compare the moles of magnesium (Mg) and hydrochloric acid (HCl) available.
Step 1: Calculate Moles of Magnesium
The molar mass of magnesium (Mg) is 24.31 g/mol.
[
\text{Moles of Mg} = \frac{55 \text{ mg}}{24.31 \text{ g/mol}} = \frac{0.055 \text{ g}}{24.31 \text{ g/mol}} \approx 0.00226 \text{ moles}
]
Step 2: Calculate Moles of HCl
The molarity equation:
[
\text{Moles} = \text{Molarity} \times \text{Volume (L)}
]
Given 0.20 M HCl and 18 mL (0.018 L):
[
\text{Moles of HCl} = 0.20 \times 0.018 = 0.0036 \text{ moles}
]
Step 3: Determine Limiting Reactant
From the balanced equation, 1 mole of Mg reacts with 2 moles of HCl.
[
\text{Moles of HCl required} = 0.00226 \times 2 = 0.00452 \text{ moles}
]
Since only 0.0036 moles of HCl are available (less than 0.00452 moles needed), HCl is the limiting reactant.
Explanation
In a chemical reaction, the limiting reactant is the one that gets completely consumed first, thus determining the maximum amount of product formed. Here, HCl is the limiting reactant because there is not enough of it to completely react with all the magnesium present. Even though there are 0.00226 moles of Mg available, there are only 0.0036 moles of HCl, which is less than the 0.00452 moles required. Because of this, HCl will be used up first, preventing further reaction. Consequently, the reaction will stop once all HCl is consumed, making it the limiting reactant.
Now, I will generate an image illustrating this reaction.
I’ve provided an illustration of the reaction between magnesium metal and hydrochloric acid, showing the production of magnesium chloride and hydrogen gas. Let me know if you need any modifications!
