67.0 Should be th3 answer
Atomic mass silicon = 28.085 u
1 mol Si ---------------- 28.085 g
? ------------------------ 245 g
245 x 1 / 28.085 =><span> 8.72 mol</span>
<span>answer A</span>
Answer:
Empirical and molecular formulas are the same, C₅H₁₀O₂.
Explanation:
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In this case, when determining the empirical and molecular formulas of organic compounds via combustion analysis, we first need to compute the moles of carbon and hydrogen via the yielded mass of carbon dioxide and water:

Next, we need to compute the mass of oxygen by subtracting the mass of carbon and hydrogen to the mass of the sample of the compound:

And consequently the moles:

Now, we need to divide the moles of each atom by the fewest moles, it in this case, those of oxygen to obtain the subscripts in the empirical formula:

Thus, the empirical formula, taken the nearest whole number is:

Now, if we divide the molar mass of the molecular formula (102.1 g/mol) by that of the empirical formula (102.1 g/mol) we infer they are both the same.
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Answer:
n= 0.03 moles
Explanation:
Using the ideal gas law:
PV=nRT
nRT=PV
n= PV/RT
n: moles
P: pressure in atm
V= volume in L
R= Avogadro's constant = 0.0821
T= Temperature in K => ºC+273.15
n= (0.925 atm)(0.80 L) / (0.0821)(300.15 K)
n= 0.03 moles
Find the mass of C in the 2.657 g CO2:
(2.657 g CO2) / (44.01 g/mol) = 0.06037 mol CO2
Since each mole of CO2 also has 1 mole of C, this is equivalent to 0.06037 mol C.
Find the mass of H in the 1.089 g H2O:
(1.089 g H2O) / (18.02 g/mol) = 0.06043 mol H2O
Since 1 mol H2O has 2 mol H, this is equivalent to (0.06043)*2 = 0.1209 mol H.
Taking the ratio of H to C: 0.1209 / 0.06037 = 2.002 ~ 2
Therefore, the empirical formula of isobutylene is CH2.