Stoichiometry Calculator | Chemical Reaction Calculator

Stoichiometry is the calculation of the quantities of reactants and products in chemical reactions. It's based on the law of conservation of mass and the law of definite proportions.

Understanding stoichiometry is crucial because it allows chemists to:

• Predict yields - Calculate how much product can be formed from given amounts of reactants
• Optimize reactions - Determine the ideal ratios of reactants to maximize efficiency
• Minimize waste - Avoid using excessive amounts of costly or hazardous chemicals
• Control quality - Ensure consistent results in manufacturing processes

From laboratory experiments to industrial manufacturing, stoichiometry forms the foundation of quantitative chemistry.

To calculate the amount of acid needed to neutralize a base, follow these steps:

1. Identify the acid and base and their formulas (e.g., HCl and NaOH)
2. Determine the number of acidic hydrogens per molecule (equivalents per mole)
3. Determine the number of basic groups per molecule (equivalents per mole)
4. Convert the amount of base to moles (if given in grams or volume)
5. Calculate the moles of acid needed based on the equivalents ratio
6. Convert the moles of acid to the desired unit (volume, mass, etc.)

The key equation is:

Moles of acid = (Moles of base × Base equivalents) ÷ Acid equivalents

Our calculator automates these calculations and handles multi-protic acids (like H₂SO₄) and bases with multiple hydroxide groups (like Ca(OH)₂).

A limiting reagent (or limiting reactant) is the reactant that is completely consumed in a chemical reaction and determines the maximum amount of product that can be formed.

To identify the limiting reagent:

1. Balance the chemical equation
2. Calculate the moles of each reactant present
3. Divide the moles of each reactant by its stoichiometric coefficient in the balanced equation
4. The reactant with the smallest result is the limiting reagent

For example, in the reaction 2H₂ + O₂ → 2H₂O, if you have 10 moles of H₂ and 4 moles of O₂:

H₂: 10 moles ÷ 2 = 5

O₂: 4 moles ÷ 1 = 4

Since O₂ gives the smaller value (4), it is the limiting reagent and will determine the maximum amount of H₂O that can be produced.

To prepare a solution of a specific molarity (moles per liter), follow these steps:

1. Calculate the molar mass of the compound from its chemical formula
2. Determine the number of moles needed: moles = molarity × volume (in liters)
3. Calculate the mass needed: mass = moles × molar mass
4. Weigh out the calculated mass of the compound
5. Dissolve the compound in a small amount of solvent (less than the final volume)
6. Transfer the solution to a volumetric flask and add solvent to reach the desired volume
7. Mix thoroughly to ensure uniform concentration

For example, to prepare 250 mL of a 0.1 M NaCl solution:

Molar mass of NaCl = 58.44 g/mol

Moles needed = 0.1 mol/L × 0.25 L = 0.025 mol

Mass needed = 0.025 mol × 58.44 g/mol = 1.461 g

Weigh 1.461 g of NaCl, dissolve it in water, and adjust the volume to 250 mL.

Theoretical yield is the maximum amount of product that could be formed in a chemical reaction based on the limiting reagent. Percent yield compares the actual amount obtained to this theoretical maximum.

To calculate theoretical yield:

1. Identify the limiting reagent in the reaction
2. Calculate the moles of limiting reagent available
3. Use the balanced equation to determine the moles of product that could form
4. Convert moles of product to mass using the molar mass

The percent yield is calculated as:

Percent yield = (Actual yield ÷ Theoretical yield) × 100%

For example, if the theoretical yield of a reaction is 10.0 g but you only obtain 8.5 g:

Percent yield = (8.5 g ÷ 10.0 g) × 100% = 85%

Percent yields less than 100% are common due to factors such as competing reactions, incomplete reactions, product loss during purification, or measurement errors.

The formula C₁V₁ = C₂V₂ is used for dilution calculations where:

• C₁ is the initial concentration
• V₁ is the initial volume
• C₂ is the final concentration after dilution
• V₂ is the final volume after dilution

This equation is derived from the principle that the number of moles of solute remains constant during dilution. It can be used to calculate any one of the four variables when the other three are known.

Common applications include:

• Preparing a diluted solution from a concentrated stock solution
• Determining how much solvent to add to reach a target concentration
• Calculating the final concentration after adding solvent
• Determining how much concentrated solution is needed to prepare a specific volume of diluted solution

For example, to dilute 10 mL of a 5 M solution to 0.5 M:

V₂ = (C₁ × V₁) ÷ C₂ = (5 M × 10 mL) ÷ 0.5 M = 100 mL

This means you need to dilute the 10 mL of 5 M solution to a final volume of 100 mL to achieve a 0.5 M concentration.

Calculating the amount of sulfuric acid needed to neutralize an amine requires considering the stoichiometry of the reaction and the properties of both compounds:

1. Determine the moles of amine present (from mass, volume, and concentration)
2. Identify how many protons each amine molecule can accept (usually one per nitrogen atom)
3. Consider that sulfuric acid (H₂SO₄) can donate two protons per molecule
4. Calculate the moles of H₂SO₄ needed: moles H₂SO₄ = (moles amine × amine equivalents) ÷ 2
5. Convert moles of H₂SO₄ to volume using concentration and density

For example, to neutralize 3 mL of a primary amine (R-NH₂) with 13% w/w sulfuric acid:

First convert the amine volume to moles, then calculate the acid needed based on the 2:1 stoichiometry (two amine molecules per sulfuric acid molecule).

Our amine neutralization calculator handles these calculations automatically, accounting for acid concentration, density corrections, and multi-basic amines like ethylenediamine.