Question

Question 1-6 are one question with different answers answer the question

Answer 1

Note that 2 moles of H2O produce 1 mole of H2. In grams, this corresponds to 36g of water produce 2g of H2

Step-by-step explanation:

Answer 2

Step 1 - Finding the relation in moles in the reaction equation

As we have previously seen working on a similar problem, the bigger numbers that come before the formula of the substance expresses a proportion in moles between all the reactants and the products.

The reaction given in this exercise is:

`2K_((s))+2H_2O_((l))\to H_(2(g))+2\text{KOH}_((aq))`

Note that 2 moles of K react with 2 moles of H2O, producing 1 mole of H2 and 2 moles of KOH.

Step 2 - Converting a relation in moles to a relation in grams

We can convert this relation in moles to a relation in grams by multiplying each number of moles by the molar mass of each substance. The molar masses are:

`\begin{gathered} K\to39\text{ g/mol} \\ H_2O\to18\text{ g/mol} \\ H_2\to2\text{ g/mol} \\ \text{KOH}\to56\text{ g/mol} \end{gathered}`

Converting to grams:

`\begin{gathered} K\to2*39=78g \\ H_2O\to2*18=36g \\ H_2\to1*2=2g \\ \text{KOH}\to2*56=112g \end{gathered}`

We can state thus that 78g of K react with 36g of water, producing 2g of H2 and 112g of KOH. This is a fixed proportion, like a cake recipe.

Step 3 - Using the information to answer the exercise

1) Note that 2 moles of K produces 2 moles of KOH. Therefore, we would need exactly 2 moles of K.

2) Note that 2 moles of K, as we have previously calculated in step 2, corresponds to 78 g.

3) Note that 2 moles of K produces 1 mole of H2. Since this is a fixed proportion, we can set the following relation:

`\begin{gathered} 2\text{ moles of K produces --- 1 mole of H2} \\ 3\text{ moles of K would produce -- x} \\ \\ x=(3*1)/(2)\text{=1}.5\text{ moles of H2} \end{gathered}`

It would be produced thus 1.5 moles of H2.

4) As we have seen in 3), we would produce 1.5 moles of H2. Since its molar mass is 2g/mol, we would produce, in grams:

`m=1.5*2=3g`

3g of H2 would be produced.

5) Note that 2 moles of H2O produce 1 mole of H2. In grams, this corresponds to 36g of water produce 2g of H2.