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4 years ago

2.7g of aluminum metal is placed into 200g of

Chemistry

1 answer:

ICE Princess25 [194]4 years ago

6 0

Answer:

2Al + 6HCl--> 2AlCl3 + 3H2

take the atomic mass of Al =27.0, Cl = 35.5, and H= 1.0,

no. of moles = .mass / molar mass

no. of moles of Al placed = 2.7 / 27.0

=0.1 mol

Assuming Al is limiting (because the concentration nor volume of HCl solution is given).

From the equation, the mole ratio of Al : AlCl3 = 2:2 = 1: 1,

meaning for each 1 mole of Al reacted, it gives out 1 mole of AlCl3. This also means the no. of moles of Al reacted equals to the no. of moles of AlCl3 produced, which is 0.1 mole.

mass = no. of moles x molar mass

hence,

mass of AlCl3 produced = 0.1 / (27 + 35.5x3)

= 0.00075 g

c. since this question is unclear, and the concentration nor volume of HCl solution is given, part c cannot be answered. Please let me know if you have any more info regarding it! thanks :)

d. From the equation, the mole ratio of Al:H2 = 2:3, meaning every 2 moles of Al reacted, gives out 3 moles of hydrogen.

using this ratio, no. of moles of H2 produced will = 0.1 x 3 / 2

=0.15 mol

At STP, the molar volume of gas is 22.4 dm3 mol-1,

volume = no. of moles x molar volume

hence volume of H2 obtained = 0.15 x 22.4

= 3.36 dm3

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Answer:

Make me Brilliant

Explanation:

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3 years ago

A sample of gas is held at 100oc at a volume of 20 L.if the volume is increased to 40 L what is the new temperature of the gas i

ElenaW [278]

Answer:

470 °C

Explanation:

This looks like a case where we can use Charles’ Law:

$\dfrac{V_{1}}{T_{1}} =\dfrac{V_{2}}{T_{2}}$

Data:

V₁ = 20 L; T₁ = 100 °C

V₂ = 40 L; T₂ = ?

Calculations:

(a) Convert the temperature to kelvins

T₁ = (100 + 273.15) K = 373.15 K

(b) Calculate the new temperature

$\begin{array}{rcl}\dfrac{V_{1}}{T_{1}}& =&\dfrac{V_{2}}{T_{2}}\\\\ \dfrac{\text{20 L}}{\text{373.15 K}} &=&\dfrac{\text{40 L}}{T_{2}}\\\\{\text{15 000 K}} & = & 20T_{2}\\T_{2} & = &\dfrac{\text{15 000 K}}{20 }\\\\T_{2} & = & \textbf{750 K}\\\end{array}$

Note: The answer can have only two significant figures because that is all you gave for the volumes.

(c) Convert the temperature to Celsius

T₂ = (750 – 273.15) °C = 470 °C

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3 years ago

Name two compounds with more exothermic lattice energies than scandium oxide and justify your choice.

N76 [4]

Answer:

1 . $Al_2O_3$

2. $TiO_2$

Explanation:

The more stable the ionic compound, the more is it lattice energy.

The more the charge on the cation and the anion, the greater is the lattice energy.
The less the size of the cation and the anion, the greater is the lattice energy.

Scandium oxide ( $Sc_2O_3$ ) is an oxide in which $Sc^{3+}$ behaves as cation and $O^{2-}$ behaves as anion.

The compounds which has higher lattice energy than scandium oxide are:

1 . $Al_2O_3$

This is because the charge are same on the cation and the anion as in the case of the Scandium oxide but the size of the cation $Al^{3+}$ is smaller than $Sc^{3+}$ . Thus, this corresponds to higher lattice energy.

2. $TiO_2$

This is because the charge on the cation $Ti^{4+}$ is greater than that of $Sc^{3+}$ and also the size of the cation $Ti^{4+}$ is smaller than $Sc^{3+}$ . Thus, this corresponds to higher lattice energy.

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3 years ago

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