Question

You react chemical \(A\) with chemical \(B\) to make one product. It takes 100 of \(A\) to react completely with 20 \(\mathrm{g}\) of \(B\) . What is the mass of the product? a. less than 10 g b. between 20 and 100 g c. between 100 and 120 g d. exactly 120 g e. more than 120 g

Short answer

The mass of the product is exactly 120 g (answer choice d).

Step-by-step solution

Understanding the Conservation of Mass Principle

In a chemical reaction, mass is conserved. This means that the total mass of the reactants (chemicals A and B) will be equal to the total mass of the product(s).

Identifying the mass of reactants

According to the problem, we have 100 g of chemical A and 20 g of chemical B. We need to find the total mass of these reactants.

Calculating the mass of the reactants

To find the total mass of the reactants, we simply add the mass of chemical A and the mass of chemical B: Total mass of reactants = mass of chemical A + mass of chemical B Total mass of reactants = 100 g + 20 g

Solving for the mass of the reactants

Now, let's calculate the total mass of the reactants: Total mass of reactants = 100 g + 20 g Total mass of reactants = 120 g

Comparing the mass of the product to the answer choices

Since the mass of the product should equal the total mass of the reactants (because of mass conservation), we can deduce that the mass of the product is 120 g. Comparing this value to the answer choices, we find that the correct answer is: d. exactly 120 g

Key concepts

Chemical Reactions

In any chemical reaction, substances known as reactants interact with each other to form new substances called products. These transformations involve breaking and forming bonds at the atomic level. Imagine mixing baking soda and vinegar to create carbon dioxide gas or combining hydrogen and oxygen to form water. This principle is universal for all chemical reactions.
In the context of our exercise, chemical A reacts with chemical B to produce a new substance. The question is about determining the mass of this product, using the information provided about the reactants.
Understanding chemical reactions is crucial because they explain how substances transform in nature, from rusting iron to digesting food.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It allows chemists to predict how much of a reactant is needed to produce a desired amount of product. The principle heavily relies on balanced chemical equations, which state the relationship between the amounts of reactants and products.
For the given exercise, stoichiometry helps us understand that 100 grams of A and 20 grams of B react in a one-to-one relationship. By applying stoichiometry, you can determine that the sum of these masses will equal the mass of the product, in line with the principle of mass conservation.
Mastering stoichiometry is key in fields like pharmacology and industrial chemistry, where precise chemical quantities are paramount.

Mass Calculation

Mass calculation involves finding the total mass of reactants or products in a chemical reaction. This is done by adding the individual masses together.
In the exercise, we needed to figure out the total mass of chemicals A and B to understand the mass of the product. We added 100 grams of chemical A with 20 grams of chemical B. This simple addition yields the total mass of 120 grams. Remember, mass calculation is straightforward but essential for accurately analyzing chemical reactions.
Correct mass calculation ensures that chemical reactions proceed efficiently and safely, especially in lab settings.

Reactants and Products

Reactants are the starting materials in a chemical reaction, while products are the substances formed as a result of the reaction. Understanding which substances are reactants and which are products is crucial for analyzing and predicting the outcome of chemical equations.
In our example, chemicals A and B are the reactants that combine to form a single product. The mass of this product is equivalent to the combined mass of the reactants, emphasizing the principle of mass conservation.
Grasping these concepts allows us to predict quantities and masses of products formed during a reaction, helping in practical applications like manufacturing, environmental science, and even cooking.