When copper(II) oxide is heated in hydrogen gas, the...

When copper(II) oxide is heated in hydrogen gas, the following reaction takes place. $$ \mathrm{CuO}(s)+\mathrm{H}_{2}(g) \longrightarrow \mathrm{Cu}(s)+\mathrm{H}_{2} \mathrm{O}(g) $$ A copper rod coated with copper(II) oxide has a mass of $38.72 \mathrm{~g}$. The rod is heated and made to react with $5.67 \mathrm{~L}$ of hydrogen gas, whose density at the conditions of the experiment is $0.0519 \mathrm{~g} / \mathrm{L}$. (a) How many grams of $\mathrm{CuO}$ were converted to Cu? (b) What is the mass of the copper after all the hydrogen is consumed? (Assume that $\mathrm{CuO}$ is converted only to Cu.)

When copper(II) oxide is heated in hydrogen gas, the following reaction takes place.
$$
\mathrm{CuO}(s)+\mathrm{H}_{2}(g) \longrightarrow \mathrm{Cu}(s)+\mathrm{H}_{2} \mathrm{O}(g)
$$
A copper rod coated with copper(II) oxide has a mass of $38.72 \mathrm{~g}$. The rod is heated and made to react with $5.67 \mathrm{~L}$ of hydrogen gas, whose density at the conditions of the experiment is $0.0519 \mathrm{~g} / \mathrm{L}$.
(a) How many grams of $\mathrm{CuO}$ were converted to Cu?
(b) What is the mass of the copper after all the hydrogen is consumed? (Assume that $\mathrm{CuO}$ is converted only to Cu.)

Key Concepts

Stoichiometry

Stoichiometry involves the quantitative relationships between reactants and products in a chemical reaction. By using the mole ratios established by a balanced chemical equation, it allows for the calculation of masses, volumes, and moles of reactants consumed and products formed.

Limiting Reagent

The concept of the limiting reagent is crucial when one reactant is present in a quantity that will be consumed before the others, thus determining the maximum amount of product that can be formed. Identifying the limiting reagent is essential in accurately predicting the yield of a reaction.

Balanced Chemical Equations

A balanced chemical equation represents the conservation of atoms and mass in a reaction, providing the necessary mole ratios between reactants and products. This ensures that calculations based on the reaction are consistent with the law of conservation of mass.

Molar Mass and Mass-Mole Conversions

Molar mass is the mass of one mole of a substance and is used to convert between the mass of a substance and the number of moles. These conversions are a fundamental part of stoichiometry, enabling quantitative predictions about chemical reactions.

Density and Gas Volume Relations

Density connects the mass and volume of a substance, and in the context of gases, it allows the conversion of a measured volume to mass (or moles) based on the conditions of the gas. This is particularly useful in stoichiometric calculations involving gaseous reactants.

Transcript

00:01 Okay, so this is a limiting reactant problem, and we know that's true because we're given amounts of both reactants.

00:07 So the first thing we're going to do is try to figure out who's our limiting reactant.

00:12 So what i'm going to do is i'm going to take the mass of the copper 2 oxide, which is 38 .72 grams, and i'm going to take the 5 .67 liters of h2, and i'm basically going to do the problem twice and figure out, how many grams of copper would be formed.

00:38 And whichever one is smaller will be our limiting reactant.

00:42 Okay, so i'm going to change grams of cuo to moles of cuo.

00:49 I picked copper because they're asking us about copper in the next part.

00:54 So moles of coo to moles of cu.

00:59 Okay.

00:59 And then moles of copper to grams of copper.

01:05 Okay, so one mole of cuo is 79.

01:10 0 .55 grams.

01:12 Our mole ratio is 1 to 1, and 1 mole of copper is 63 .55.

01:19 So if copper 2 oxide is our limiting reactant, we'll be able to make 30 .93 grams of copper.

01:31 So here i've got liters, but they've given me a density.

01:35 So i'm going to go ahead and change liters to grams of my hydrogen.