Question

Identify the limiting reactant in the reaction of hydrogen and ethylene (c2h4) to form c2h6, of 4.40 g of h2 and 10.5 g of c2h4 are combined. Determine the amount (in grams) of excess reactant that remains after the reaction is complete.

Answer 1

Definition : Limiting reagent is the substance in a chemical reaction that is consumed when chemical reaction is complete.

step 1 : first write the chemical reaction and then balanced the chemical equation

`C_(2)H_(4) + H_(2) \rightarrow C_(2)H_(6)`

step 2 : convert given masses into moles.

`\text{ moles of } C_(2)H_(4)=10.5 (g)/ 28 (\text{ g/mole)} = 0.375 \text{ moles}`

`\text{moles of }H_(2)= 0.40 (g)/ 2 (g/mole) = 0.20 moles`

step 3 : Now find the limiting reagent.

`\text{ moles of }C_(2)H_(4) \text{ in excess}= 0.375-0.20 = 0.175 \text{moles}`

Now we conclude that
`C_(2)H_(4)` is the limiting reagent.

step 4 : Amount of the excess reactant i.e
`C_(2)H_(4)`

`\text{ mass of }C_(2)H_(4)= 0.175 (moles) \ast 28 (g/mole) = 4.9 g`