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natima [27]
2 years ago
11

What is the best definition of the enthalpy change Hr

Chemistry
1 answer:
Gre4nikov [31]2 years ago
5 0

Answer:

<em>The flow of thermal energy in a system, at constant atmospheric pressure AND at thermodynamic standard temperature and pressure.</em>

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Consider the Fischer ester synthesis of methyl benzoate from benzoic acid and methanol in the presence of sulfuric acid as a cat
zlopas [31]

Answer:

48.8%

Explanation:

The reaction has a 1:1 mole ratio so;

Number of moles of benzoic acid reacted = mass/molar mass = 3.8 g/122.12 g/mol = 0.03 moles

So;

0.03 moles of methyl benzoate is formed in the reaction

Mass of methyl benzoate formed = 0.03 moles * 136.15 g/mol = 4.1 g

percent yield = actual yield/theoretical yield * 100/1

percent yield = 2.0 g/4.1 g * 100 = 48.8%

4 0
3 years ago
How do exothermic and endothermic differ
Ber [7]

Answer:

Explanation:

exothermic reactions involve release of heat whereas endothermic reaction involve absorption of heat.

6 0
2 years ago
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What should be the temperature of the solvent before adding it to the sample to be recrystallized?
Serhud [2]

Answer:

Near the boiling point of the solvent

Explanation:

The process of recrystallization is hinged on the fact that the amount of solute that can be dissolved by a solvent increases with temperature. The process involves creation of a solution by dissolving a solute in a solvent at or near its boiling point.  At the boiling point of the solvent, the solute has a greater solubility in the solvent; not much volume of  the hot solvent is required to dissolve the solute.

Before the solution is later cooled, you can now filter out insoluble impurities from the hot solvent. The quantity of the original solute drops appreciably because impurities have been removed. At this lower temperature, the solution becomes saturated and the solute can no longer be held in solution hence it forms pure crystals of solute, which can be recovered.

Recrystallization must be carried out using the proper solvent. The solute must be relatively insoluble in the solvent at room temperature but more soluble in the solvent at elevated temperature.

3 0
2 years ago
When a metal bonds with a nonmetal, the bond that is formed is a(n) ___.
bekas [8.4K]
Ionic Bond, which is the transfer of electrons of a metal to a non-metal. 
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3 years ago
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What are genes?
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C) the basic unit of inheritance

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