Stoichiometry is the calculation of the quantities of reactants and products involved in a chemical reaction based on the balanced equation. It helps determine the amount of one substance that is needed to react completely with another substance. This calculation is crucial for understanding and predicting the outcome of chemical reactions.

Stoichiometry originated in the late 18th century with the works of chemists like Jeremias Benjamin Richter. It involves quantifying the relationships between reactants and products in chemical reactions based on the law of conservation of mass. Stoichiometry has since become a fundamental concept in chemistry for calculating the amounts of substances involved in reactions.

Stoichiometry is important because it allows us to predict the quantities of reactants and products in a chemical reaction. This information is essential for designing experiments, determining the efficiency of a reaction, and ensuring that reactions proceed as expected in chemical synthesis. Understanding stoichiometry also helps in calculating the amount of reagents needed for a reaction and in determining the limiting reactant.

Stoichiometry uses coefficient ratios to relate moles of one molecule to moles of another

Calculating the mass of a product from the number of moles of reactants

APEX

calculating the mass of a product from the number of miles of reactants

Grams liquid × mol/g × Hfusion

Density (at a given temperature) is the parameter that relates the mass to the volume of any substance.

You need the balanced chemical reaction equation :
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2 K + 2 H2O ----. 2 KOH + H2

moles H2 = n H2 = ( 1.60 L ) ( 1 mol H2 / 22.4 L H2 ) = 0.07143 moles H2

moles K = n K = ( 0.07143 mol H2 ) ( 2 mol K / 1 mol H2 ) = 0.14286 moles K

mass K = m K = ( 0.14286 mol K ) ( 39.10 g K / mol K )

mass K = m K = 5.56 g of potassium <---

Answer : 5.56 g of potassium

The nearest gram is in the ones column, so we must look at the tenths column (the first number on the right of the decimal). If this number if 5 or higher then we must round up and report the value as 1.0 g or if it is lower than 5 then we report the answer as 0.0. All other numbers are irrelevant. In this case (0.[5]3525) the number we are concerned about (in the square brackets) is 5, therefore we round up and the answer is 1.0 g.