Question

How many moles of butane on complete combustion gives 18 g of water?

Answer 1

0.2 mole

We know that 1 mole of butane on complete combustion gives 5 moles of water.

• 
  `C_4H_10 + (13)/(2) O_2 \rightarrow \: 4CO_2 + 5H_2O`

Also,

• The weight of 1 mole of water = 18g
• The weight of 5 mole of water = 5 x 18 g = 90g

hence,

• 90g of water would give 1 mole butane
• 1 g of water would give 1/90 mole butane

and

• 18 g of water would give 1/90 x 18 mole butane
• 18 g of water would give 1/5 or 0.2 mole butane

Therefore, 0.2 mole of butane would give 18 g of water on complete combustion.

Answer 2

0.2 moles of butane

Step-by-step explanation:

In order to answer your question, we need to use the balanced chemical equation for the combustion of butane.

`\sf 2C_4H_(10)(g) + 13O_2(g) \rightarrow 8CO_2(g) + 10H_2O(g)`

According to the equation, 10 moles of water are produced from 2 moles of butane.

Therefore, we can use a ratio to find the moles of butane that produce 18 g of water:

`\sf \frac{2 \textsf{ moles of butane}}{10 \textsf{ moles of water}} = \frac{x \textsf{ moles of butane}}{18 \textsf{ g of water} * \frac{1 \textsf{ mole of water}}{18 \textsf{ g of water}}}`

Solving for x, we get:

`\sf x = (2 * 18 * 1)/(10 * 18) = 0.2`

Therefore, 0.2 moles of butane on complete combustion gives 18 g of water.