<span>Carbohydrates have 4 kcal per gram of carbohydrates. (Protein is also 4 kcal/gram, while fat is 9 kcal/gram).
Take the total kcal and divide by 4 kcal/gram: 72 kcal/(4 kcal/gram) = 18 grams carbohydrates.</span>
Answer:
Explanation:
- For the balanced reaction:
<em>4Fe(s) + 3O₂(g) → 2Fe₂O₃(s).</em>
It is clear that 4 mol of Fe react with 3 mol of O₂ to produce 2 mol of Fe₂O₃.
- Firstly, we need to calculate the no. of moles of 35.8 grams of Fe metal:
no. of moles of Fe = mass/molar mass = (35.8 g)/(55.845 g/mol) = 0.64 mol.
- Now, we can find the no. of moles of O₂ is needed to react with the proposed amount of Fe:
<em><u>Using cross multiplication:</u></em>
4 mol of Fe is needed to react with → 3 mol of O₂, from stichiometry.
0.64 mol of Fe is needed to react with → ??? mol of O₂.
∴ The no. of moles of O₂ needed = (3 mol)(0.64 mol)/(4 mol) = 0.48 mol.
- Finally, we can get the volume of oxygen using the information:
<em>It is known that 1 mole of any gas occupies 22.4 L at standard P and T (STP).</em>
<em></em>
<em><u>Using cross multiplication:</u></em>
1 mol of O₂ occupies → 22.4 L, at STP conditions.
0.48 mol of O₂ occupies → ??? L.
∴ The no. of liters of O₂ = (0.48 mol)(22.4 L)/(1 mol) = 10.752 L.
Hey there!:
The law of boyle is used:
initial pressure ( P1 ) = ?
initial volume ( V1 ) = 13 L
final pressure ( P2 ) = 1.8 atm
final volme ( V2 ) = 5 L
P1 *V1 = P2 * V2
P1 * 13 = 1.8 * 5
P1 * 13 = 9
P1 = 9 / 13
P1 = 0.692 atm
Hope this helps!
