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2 years ago

For each pair below, select the sample that contains the largest number of moles. Pair A 2.50 g O2 2.50 g N2

Chemistry

2 answers:

wel2 years ago

8 0

Answer:

Pair A : 2.50 g N2 Pair B : 21.5 g n2 Pair C : 0.081 CO2

Explanation:

raketka [301]2 years ago

4 0

Answer:

Explanation:

Pair 2.50g of O₂ and 2.50g of N₂

The atoms sample with the largest number of moles since the masses are the same would be the one with lowest molar mass according the the equation below:

Number of moles = $\frac{mass }{molarmass}$

Atomic mass of O = 16g and N = 14g

Molar mass of O₂ = 16 x 2 = 32gmol⁻¹

Molar mass of N₂ = 14 x 2 = 28gmol⁻¹

Number of moles of O₂ = $\frac{2.5}{32}$ = 0.078mole

Number of moles of N₂ = $\frac{2.5}{28}$ = 0.089mole

We see that N₂ has the largest number of moles

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We use Avogadro's Number, 6.02*10²³: the number of particles (atoms, molecules, etc.) in 1 mole of a substance. In this case, the particles are atoms of boron.

$\frac {6.02*10^{23} \ atoms \ B} {1 \ mol \ B}$

Multiply by the number of moles we calculated.

$2.312673451 \ mol \ B *\frac {6.02*10^{23} \ atoms \ B} {1 \ mol \ B}$

The moles of boron cancel.

$2.312673451 *\frac {6.02*10^{23} \ atoms \ B} {1 }$

$2.312673451 *6.02*10^{23} \ atoms \ B} =1.39269195*10^{24} \ atoms \ B$

The original value of grams has 4 significant figures, so our answer should have the same. For the number we calculated, that is the thousandth place.

$1.392\underline69195*10^{24} \ atoms \ B$

The 6 tells us to round the 2 to a 3.

$1.393 *10^{24} \ atoms \ B$

25.00 grams of boron is equal to 1.393*10²⁴ atoms.

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