Question

If 5.70 g of potassium react with water, how many grams of hydrogen gas, H₂, are produced?

2 K + 2 H₂O → 2 KOH + H₂

Enter your answer rounded to the correct number of significant digits.

Answer 1

Step 1: Explanation:

A mole ratio is ​the ratio between the amounts in moles of any two compounds involved in a chemical reaction. The mole ratio can be determined by examining the coefficients in front of formulas in a balanced chemical equation.

Step 1: write the balanced chemical equation.

2 K(s) + 2 H₂O(l)---> 2 KOH(aq) + H₂(g)

Step2: calculate the moles of K.

we know, moles = mass given / molar mass = ( 5.7 g / 39 g/mol ) = 0.146 mol

Step 3: Calculate the moles of hydrogen gas

2 K(s) + 2 H₂O(l)---> 2 KOH(aq) + H₂(g)

According to the reaction:
2 mol of K produce 1 mol of H₂ gas
so, 0.146 mol of Al will produce=( 1 mol of H₂ / 2 mol of K )×0.146 mol of K = 0.073 mol of H₂

Step 4: Calculation of hydrogen gas  produced

we get moles of hydrogen that can be produced = 0.073 mol

Mass of H₂ produced =( moles×molar mass ) = (0.073 mol × 2.01588 g/mol ) = 0.147 g

Hydrogen gas are produced = 0.147 g