# Calculating Mass from Chemical Reaction

• physicsnobrain
In summary, the mass of alum that can be prepared from 1.340g of Al is 23.55g, with Al being the limiting reagent and using the molar ratio and molar mass of alum to calculate for the moles and mass.

## Homework Statement

what is the mass of alum that can be prepared from 1.340g of Al.

## Homework Equations

2Al+2KOH+4H2SO4+22H2O ---> 3H2 + 2KAl(SO4)2 * 12H2O

## The Attempt at a Solution

given Al is the limiting reagent. Find the moles of Al using n=m/M

I find Al moles to be 0.049662mol.

Now multiply this by the molar ratio of 2/2 (which is 1) to find the moles of alum produced.

now calculate for the mass, m = nM. The molar mass of alum is 474.3g/mol. I find the mass of alum to be 23.55g.

Am I right?

Looks OK to me.

## 1. How do you calculate the mass of a substance involved in a chemical reaction?

The mass of a substance can be calculated by using the formula: Mass = Number of Moles x Molar Mass. First, determine the number of moles of the substance by dividing its given amount (in grams) by its molar mass (in grams per mole). Then, multiply the number of moles by the molar mass to get the mass in grams.

## 2. What is the importance of calculating mass from a chemical reaction?

Calculating mass from a chemical reaction is important because it allows scientists to determine the amount of each substance involved in the reaction. This information is crucial for understanding the stoichiometry of the reaction, predicting product yields, and determining the efficiency of the reaction.

## 3. Can mass be conserved in a chemical reaction?

Yes, mass is always conserved in a chemical reaction. This means that the total mass of the reactants will always equal the total mass of the products. This is known as the law of conservation of mass, which states that matter cannot be created or destroyed, only transformed.

## 4. How can you calculate the mass of a product based on the mass of the reactants?

To calculate the mass of a product, you can use the concept of mole ratios. This involves converting the mass of the reactant(s) to moles and then using the mole ratio between the reactant(s) and the product to determine the mass of the product. The mole ratio can be found by looking at the coefficients of the balanced chemical equation.

## 5. What are some common sources of error when calculating mass from a chemical reaction?

Some common sources of error when calculating mass from a chemical reaction include human error in measuring and recording data, incomplete reactions, and impurities in the reactants or products. It is important to accurately measure and record data and to use pure substances in order to minimize these sources of error.