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3 years ago

The number of moles in 250 L of He gas at STP is ________ mol, Round to a whole number,

Chemistry

1 answer:

7nadin3 [17]3 years ago

7 0

Answer: The number of moles in 250.0 L of He at STP is 11.0 mole.

Explanation:

It is known that 1.0 mole of a gas at STP conditions will occupy 22.7 L.

To show this information: STP means that T = 0.0 °C = 273.15 K and P = 1.0 kPa = (100/101.325) = 0.9869 atm.

From the ideal gas law: PV = nRT.

Where, P is the pressure in atm <em>(P = 1.0 atm at STP).</em>

V is the volume in L.

n is the number of moles (n = 1.0 mole).

R is the general gas constant (R = 0.0821 L.atm/mol.K).

T is the temperature in K (T = 273.15 K at STP).

and now we can get the volume of 1.0 mole at STP: V = nRT/P

V = (1.0 mole x 0.0821 L.atm/mol.K x 273.15 K) / (0.9869 atm) = 22.7 L.

Now, we can get the number of moles of 250.0 L of He at STP:

<em>Using cross multiplication:</em>

1.0 mole → 22.7 L

??? mole → 250.0 L

The number of moles in 250.0 L of He at STP = (250.0 L x 1.0 mole) / (22.7 L) = 11.01 mole ≅ 11.0 mole.

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<h3>Answer:</h3>

Lead-205 (Pb-205)

<h3>Explanation:</h3>

<u>We are given;</u>

An atom of Po-209

We are supposed to identify its product after an alpha decay;

Polonium-209 has a mass number of 209 and an atomic number of 84.
When an element undergoes an alpha decay, the mass number decreases by 4 while the atomic number decreases by 2.
Therefore, when Po-209 undergoes alpha decay it results to the formation of a product with a mass number of 205 and atomic number of 82.
The product from this decay is Pb-205, because Pb-205 has a mass number of 205 and atomic number 82.

The equation for the decay is;

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3 years ago

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Andru [333]

Answer: 1.8 moles Fe and 2.7 moles $CO_2$ are produced.

Explanation:

The balanced chemical reaction is:

$Fe_2O_3+3CO\rightarrow 2Fe+3CO_2$

According to stoichiometry :

3 moles of $CO$ require 1 mole of $Fe_2O_3$

Thus 2.7 moles of $CO$ will require= $\frac{1}{3}\times 2.7=0.9moles$ of $Fe_2O_3$

Thus $CO$ is the limiting reagent as it limits the formation of product and $Fe_2O_3$ is the excess reagent.

As 3 moles of $CO$ give = 2 moles of $Fe$ and 3 moles of $CO_2$

Thus 2.7 moles of $CO$ will give = $\frac{2}{3}\times 2.7=1.8moles$ of $Fe$ and $\frac{3}{3}\times 2.7=2.7moles$ of $CO_2$

Thus 1.8 moles Fe and 2.7 moles $CO_2$ are produced.

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Ethylenediamine (en) forms an octahedral complex with Ni2+(aq) with the formula [Ni(en)3]2+. Ni2+(aq) + 3 en ⇌ [Ni(en)3]2+(aq) K

yawa3891 [41]

Answer:

$3.125\times 10^{-19} mol/L$ is the concentration of $Ni^{2+}(aq)$ in the solution.

Explanation:

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Concentration of nickel ion = $[Ni^{2+}]=x$

Concentration of nickel complex= $[[Ni(en)_3]^{2+}]=\frac{0.16 mol}{2 L}=0.08 mol/L$

Concentration of ethylenediamine = $[en]=\frac{0.80 mol}{2 L}=0.40 mol/L$

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