Answer:
Hello
The answer is 18,7(b)
Explanation:we don't know the value of o² so at first we should put (x)instead of gr of o²and then write 1molO²/32grO²×2mol SO²/3mol O²×64gr SO²/1molSO²=25 gr SO².and then just find the value of (x).
The last one will be It's better to use the average data instead of the single trail because the average you don't have to multiply add subtract and all that nonsense but if you use the single trail you will have to do all the adding multiplying etc.
Answer:
25%
Explanation:
Half life means that 50% of the sample is gone at 3.3 years. This means that an additional 3.3 years (total 6.6 years) will reduce the sample a further 50% from the point at 3.3 years. In numbers, this means 50% of 50% (0.50*0.50), which is 25%.
23.01 g of zinc (Zn)
Explanation:
We have the following chemical reaction:
3 Zn + 2 H₃PO₄ = 3 H₂ + Zn₃(PO₄)₂
number of moles = mass / molar weight
number of moles of phosphoric acid = 23.1 / 98 = 0.236 moles
Taking in account the chemical reaction, we devise the following reasoning:
if 2 moles of H₃PO₄ are reacting with 3 moles of Zn
then 0.236 moles of H₃PO₄ are reacting with X moles of Zn
X = (0.236 × 3) / 2 = 0.354 moles of Zn
mass = number of moles × molar weight
mass of Zn = 0.354 × 65 = 23.01 g
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number of moles
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