Answer:
The answer to your question is 25 grams
Explanation:
Data
half-life = 5730 years
sample = 200 g
after 3 half-lives
Process
Calculate the amount of sample after one, two and three half-lives.
After each half-life, that of sample is half the previous amount.
Number of half-lives Amount of sample
0 200 g
1 100 g
2 50 g
3 25 g
The melting point of gallium is 85.59°F (29.77°C).
Answer:
Speed, v = 5 m/s
Explanation:
The length of the football field, l = 100 m
the person takes 20 seconds to run its length
v=
t
d
v=
20 s
100 m
v=5 m/s
Answer: 5
Explanation: you divide the distance by the time and get the speed.
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.
