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3 years ago

Calculate the number of molecules?

Chemistry

1 answer:

Ann [662]3 years ago

8 0

87.33 X 10^15 molecules

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Caffeine, a molecule found in coffee, tea, and certain soft drinks, contains C, H, O, and N. Combustion of 10.0 g of caffeine pr

denis-greek [22]

Answer:

194 g/mol.

Explanation:

Hello,

In this case, one first must compute the mass of each element as shown below:

$C=18.13gCO_2*\frac{12gC}{44gCO_2} =4.945gC\\H=4.639gH_2O*\frac{2.016gH}{18.0152gH_2O}=0.519gH\\N=2.885gN_2\\O=10.0g-4.945g-0.519g-2.885g=1.651gO$

Next, the corresponding moles:

$C=4.945gC*\frac{1molC}{12gC}=0.412mol\\H=0.519gH*\frac{1molH}{1gH}=0.519mol\\N=2.885gN*\frac{1molN}{14gN}=0.206molN\\O=1.648gO*\frac{1molO}{16gO} =0.103molO$

Then, each element's subscripts is found to be:

$C=\frac{0.412}{0.103}=4\\H=\frac{0.519}{0.103}=5\\N=\frac{0.206}{0.103} =2\\O=\frac{0.103}{0.103}=1$

Therefore, the empirical formula is:

$C_4H_5N_2O$

Nonetheless, it has a molar mass of 97bg/mol, thereby, by multiplying such formula by 2 one gets:

$C_8H_10N_4O_2$

Which has a molar mass of 194 g/mol being correctly contained in the given interval.

Best regards.

8 0

3 years ago

A volume of 25cm3 of a carbonate solution of concentration 0.2mol dm-3 was neutralized by 20 cm3 of acid of concentration 0.5 mo

Galina-37 [17]

Answer: 1 mol of carbonate to 2 mol of acid

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution in ml}}$

a) $\text{Moles of carbonate}=\frac{0.2moldm^{-3}\times 25cm^3}{1000}=0.005mol$

b) $\text{Moles of acid}=\frac{0.5moldm^{-3}\times 20cm^3}{1000}=0.01mol$

Thus the mole ratio of carbonate to acid is = $\frac{0.005}{0.01}=\frac{1}{2}$

7 0

3 years ago

Which of these pathogens can be killed by antibiotics?

Alisiya [41]

Answer:

it's c.

Explanation:

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3 years ago

What is the formula for heat of fusion?

spin [16.1K]

Answer:

The formula used to calculate heat of fusion:

q = m·ΔH f

Explanation:

The formula used to calculate heat of fusion:

q = m·ΔH f

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3 years ago

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Which of the following measurements is expressed to three significant figures?

IRINA_888 [86]

we need the three measurements to be able to asses significant figures.

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4 years ago

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