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3 years ago

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0.28gram of NH3 on decomposition gave 0.25gram of nitrogen and hydrogen. Find the volume of hydrogen evolved at Ntp. (2gram hydr

ogen at NTP= 22.4liter)

1 answer:

hodyreva [135]3 years ago

7 0

The volume of H₂ evolved at NTP=0.336 L

<h3>Further explanation</h3>

Reaction

Decomposition of NH₃

2NH₃ ⇒ N₂ + 3H₂

conservation mass : mass reactants=mass product

0.28 NH₃= 0.25 N₂ + 0.03 H₂

2 g H₂ = 22.4 L

so for 0.03 g :

$\tt \dfrac{0.03}{2}\times 22.4=0.336$

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Solution : Given,

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Molar mass of helium = 4 g/mole

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As we are given gases in percent, that means 10 g of oxygen gas, 50 g of helium gas and 40 g of nitrogen gas present in 100 g of mixture.

First we have to calculate the moles of oxygen, helium and nitrogen gas.

$\text{Moles of }O_2=\frac{\text{Mass of }O_2}{\text{Molar mass of }O_2}=\frac{10g}{32g/mole}=0.3125moles$

$\text{Moles of }He=\frac{\text{Mass of }He}{\text{Molar mass of }He}=\frac{50g}{4g/mole}=12.5moles$

$\text{Moles of }N_2=\frac{\text{Mass of }N_2}{\text{Molar mass of }N_2}=\frac{40g}{28g/mole}=1.428moles$

Now we have to calculate the total number of moles of gas mixture.

$\text{Total number of moles of gas}=\text{Moles of oxygen gas}+\text{Mole of helium gas}+\text{Moles of nitrogen gas}$

$\text{Total number of moles of gas}=0.3125+12.5+1.428=14.24moles$

Now we have to calculate the moles fraction of helium gas.

$\text{Mole fraction of He gas}=\frac{\text{Moles of He gas}}{\text{Total number of moles of gas}}=\frac{12.5}{14.25}=0.877$

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To separate the a mixture of chalk and potassium chloride, we must not that chalk is calcium carbonate compound, CaCO₃.

Calcium carbonate has low solubility in water. KCl is readily soluble in water and it is also an ionic compound.

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We first pour pure water into the mixture. Water will dissolve the potassium chloride readily.

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$\rm HCl\; (aq) + NaOH\; (aq) \to NaCl\; (aq) + H_2O\; (l)$ .

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$\displaystyle \frac{n(\mathrm{HCl})}{n(\mathrm{NaOH})} = 1$ .

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3 years ago

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4 years ago

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