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777dan777 [17]
3 years ago
8

The thermite reaction, in which powdered aluminum reacts with iron oxide, is highly exothermic: 2Al(s) + F e2O3 (s)→A l2O 3 (s) 

+ 2Fe(s) Use standard enthalpies of formation to find ΔH ∘ rxn for the thermite reaction.
Chemistry
1 answer:
bija089 [108]3 years ago
4 0
For this problem, we use the Hess' Law.

ΔHrxn = ∑(ν*Hf of products) - ∑(ν*Hf of reactants)

The ν represents the corresponding stoichiometric coefficients of the substances, while Hf is the heat of formation. For pure elements, Hf = 0.

Hf of Al₂O₃ = <span>−1676.4 kJ/mol
</span>Hf of Fe₂O₃ = <span>-826.0 kJ/mol

Thus,

</span>ΔHrxn = 1*−1676.4 kJ/mol + 1*-826.0 kJ/mol
<em>ΔHrxn = -2502.4 kJ/mol</em>
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calculate the volume occupied by 10g of propane gas, under normal conditions of temperature and pressure
andriy [413]

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5.5 L

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First we <u>convert 10 g of propane gas</u> (C₃H₈) to moles, using its <em>molar mass</em>:

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Then we <u>use the PV=nRT formula</u>, where:

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3 0
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Match the following names of glassware with what you would use them for.
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A) Graduated pipette – Glassware used to accurately transfer small volumes.

B) Volumetric pipette – Glassware used to accurately transfer a small, single volume.

C) Beaker – Glassware best used when greater access to the contents is needed.

D) Buret – Glassware used to deliver a volume not known in advance.

E) Erlenmeyer flask – Glassware used to prevent splashing or evaporation.

F) Volumetric flask – Glassware used to make accurate solutions.

Explanation:

Graduated pipette – Glassware used to accurately transfer small volumes.

A graduated pipette is a pipette, which has a scale that shows its volume marked along the tube. It is used to transfer small volumes accurately.

Volumetric pipette – Glassware used to accurately transfer a small, single volume.

A volumetric pipette is a pipette, which has a ring like marking that is its calibrated volume. So it is used to transfer a single and small volume only. This pipette is used in volumetric analysis.

Beaker – Glassware best used when greater access to the contents is needed.

Beaker is the most widely used glassware in the laboratory. They are used to transfer large volume with less accuracy. They are of different sizes depends on the size of volumes ranging from 10 mL to 1000 mL.

Buret – Glassware used to deliver a volume not known in advance.

Buret is the most important glassware in the quantitative analysis. It has a glass tube with scale which measures the volume and a stopcock at one end from which the solvent is dispersed. It is used to measure the volume of the liquid during the titration in the quantitative analysis.

Erlenmeyer flask – Glassware used to prevent splashing or evaporation.

The most common names of Erlenmeyer flask are conical flask and titration flask. This flask has flat bottom, conical body and cylindrical neck which prevent splashing and evaporation. This flask is used in the titration process in the quantitative analysis. The solvent from the buret is delivered into the conical flask during the titration process.

Volumetric flask – Glassware used to make accurate solutions.

The volumetric flask is also an important glassware in the analytical laboratory. It is used to prepare standard solutions. It is a flask which has a ring like marking that is its calibrated volume. The mentioned volume of volumetric flask is calibrated to have accurate volume.

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