Question

In the lab, a student collects hydrogen gas over water in a eudiometer. The hydrogen gas is produced when a piece of magnesium metal reacts with excess hydrochloric acid. Part 1: (a) Write the balanced chemical equation for this reaction. Include the states of matter. Mg(s) + 2HCl (aq) — H2 (8) +MgCl, (aq) Part 2 out of 2 (b) How many moles of hydrogen gas are collected if 3.09 g of magnesium metal is used in the reaction? Report prc Moles of hydrogen gas mol H2​

Answer 1

Moles of Hydrogen gas collected : 0.127

Further explanation

The reaction coefficient in a chemical equation shows the mole ratio of the components of the reactants and products

If one mole of the reactant or product is known, then we can determine the moles of the other compounds involved in the reaction

Reaction

Mg(s)+2HCl(aq)⇒H₂(g)+MgCl₂(aq)

mass of Mg=3.09 g

mol Mg (Ar= 24,305 g/mol) :

`\tt mol=(mass)/(Ar)\\\\mol=(3.09)/( 24,305)\\\\mol=0.127`

Magnesium metal reacts with excess Hydrochloric acid, so Mg as a limiting reactant and moles of product is based on moles of Mg

From the equation, moles ratio Mg : H₂ = 1 : 1, so moles H₂ :

`\tt (1)/(1)* 0.127=0.127`