Question

Analyzing Results Very seldom are chemists able to achieve a 100% yield of a product from a chemical reaction. However, the yield of a reaction is usually important because of the expense involved in producing less product. For example, when magnesium metal is heated in a crucible at high temperatures, the product magnesium oxide, MgO, is formed. Based on your analysis of the reaction, describe some of the actions that you would take to increase your percentage yield. The reaction is as follows: $$ 2 \mathrm{Mg}(s)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{MgO}(s) $$

Short answer

Ensure reactants are pure, maintain optimal temperature and accurate measurements, use excess oxygen, minimize side reactions, and collect the product efficiently.

Step-by-step solution

- Understand the Reaction

The given reaction involves the heating of magnesium metal in the presence of oxygen to form magnesium oxide. The chemical reaction is: \[2 \mathrm{Mg}(s) + \mathrm{O}_{2}(g) \rightarrow 2 \mathrm{MgO}(s)\] This is a combination reaction where magnesium metal reacts with oxygen gas to form magnesium oxide.

- Ensure Purity of Reactants

To increase the yield, ensure that the magnesium metal is pure. Impurities can reduce the efficiency of the reaction, resulting in a lower yield.

- Maintain Optimal Temperature

Maintain high temperatures to ensure that the reaction between magnesium and oxygen proceeds to completion. The reaction is endothermic and requires sufficient heat to break bonds and form the product.

- Use Excess Oxygen

Oxygen should be supplied in excess to ensure that all the magnesium reacts completely. Limiting the amount of oxygen can limit the amount of magnesium oxide produced, thus reducing yield.

- Minimize Side Reactions

Minimize or eliminate side reactions that may consume reactants or produce unwanted products. This can be achieved by ensuring the reaction environment is free from contaminants that might react with magnesium or oxygen.

- Optimize Reaction Time

Allow sufficient time for the reaction to go to completion. Under-heating or cutting the reaction short can result in unreacted magnesium, thus decreasing yield.

- Implement Accurate Measurement

Precisely measure reactants to ensure stoichiometric ratios are followed. Any deviation from the optimal ratio can affect the yield.

- Efficient Collection of Product

Collect the magnesium oxide product efficiently. Ensure that no product is lost during the process of collection and weighing.

Key concepts

reaction yield

The reaction yield is the amount of product obtained from a chemical reaction relative to the theoretical maximum amount that could be produced. Achieving a high reaction yield is vital in chemical processes, especially when dealing with costly materials.
Yield can be expressed as a percentage, often calculated using the formula: \[\begin{equation} \text{Percentage Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100\text{%} \end{equation}\]
To maximize the yield, various factors such as purity of reactants, reaction conditions, and collection methods should be optimized.
For instance, in the case of the combination reaction between magnesium and oxygen forming magnesium oxide, ensuring the reactants are pure and that conditions like temperature and oxygen supply are controlled, directly impacts the yield efficiency.

reaction efficiency

Reaction efficiency relates closely to reaction yield but encompasses the overall process efficiency, covering aspects like time, energy expenditure, and resource utilization.
Improving reaction efficiency often involves:

• Reducing energy consumption by optimizing temperatures
• Minimizing waste and unwanted by-products through careful monitoring of reaction conditions
• Maximizing resource utilization by using precise stoichiometric measurements

In our example, maintaining a high temperature and providing excess oxygen ensures that the reaction efficiency is high, as all magnesium reacts with the oxygen efficiently producing the desired amount of magnesium oxide.

combination reaction

A combination reaction, also known as a synthesis reaction, involves two or more reactants combining to form a single product.
The general form is: \[\begin{equation} A + B \rightarrow AB \end{equation}\]
In the given exercise, magnesium (\text{Mg}) reacts with oxygen (\text{O}_2) to form magnesium oxide (\text{MgO}). This kind of reaction generally releases energy, but requires the correct conditions to proceed efficiently.
Key characteristics include:

• Simplicity of having fewer products to manage and purify
• The ability to easily calculate stoichiometric ratios
• High potential yields when reactants are pure and conditions are optimal

Understanding these characteristics can help in predicting and maximizing the yield of the product.

stoichiometry

Stoichiometry is the quantitative relationship between reactants and products in a chemical reaction. It allows chemists to predict the amounts of substances consumed and produced.
For the reaction \[\begin{equation} 2 \text{Mg (s)} + \text{O}_2 \text{(g)} \rightarrow 2 \text{MgO (s)} \end{equation}\], stoichiometry tells us that two moles of magnesium react with one mole of oxygen to produce two moles of magnesium oxide.
Key principles include:

• Balancing chemical equations to ensure the law of conservation of mass
• Using molar ratios to relate quantities of reactants and products
• Converting between masses, moles, and particles

Understanding and applying stoichiometry ensures that the precise amounts of reactants are used, which is crucial for achieving high reaction yields and overall process efficiency.