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3 years ago

A chemist measures the energy change ?H during the following reaction:

Chemistry

1 answer:

Leno4ka [110]3 years ago

5 0

Answer:

(A) endothermic

(A) Yes, absorbed

Explanation:

Let's consider the following thermochemical equation.

2 Fe₂O₃(s) ⇒ 4 FeO(s) + O₂(g) ΔH = 560 kJ

Since ΔH > 0, the reaction is endothermic.

We can establish the following relations:

560 kJ are absorbed when 2 moles of Fe₂O₃ react.
The molar mass of Fe₂O₃ is 160 g/mol.

Suppose 66.6 g of Fe₂O₃ react. The heat absorbed is:

$66.6g.\frac{1mol}{160g} .\frac{560kJ}{2mol} =117kJ$

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What is the mass of 3.15 moles of calcium sulfate, CaSO4?

sammy [17]

Answer:

3.15 * 136 (136 is the molar mass of calcium sulfate). = 428 g CaSO4.

Explanation:

5 0

3 years ago

A salt contains only magnesium and one of the halide ions. A 0.0776-g sample of the salt was dissolved in water, and an excess o

sdas [7]

Answer:

The formula of the magnesium halide is MgF₂

Explanation:

All halides, X, produce a salt with Mg with the formula:

MgX₂

-There are 2 moles of the halide ion per mole of Mg-

With the mass of the MgSO₄ we can find moles of magnesium sulfate = Moles Mg.

With moles of Mg we can know the moles of the halide -1 mole Mg = 2 moles of Halide-

And we can find the mass of Mg in the 0.0776g sample. Subtracting we can find the mass of the halide and, with the mass and moles of the halide we can find its molecular weight and its identity:

Moles MgSO₄ -Molar mass: 120.366g/mol- = Moles Mg:

0.150g * (1mol / 120.366g) = 1.2462x10⁻³ moles Mg

Moles halide:

1.2462x10⁻³ moles Mg * 2 = 2.4924x10⁻³ moles Halide

Mass Mg -Molar mass: 24.305g/mol:

1.2462x10⁻³ moles Mg * (24.305g / mol) = 0.0303g Mg

Mass halide:

0.0776g - 0.0303g Mg = 0.0473g

Molecular weight of the halide:

0.0473g / 2.4924x10⁻³ moles =

18.98g/mol

This molecular weight is the molecular weight of Fluoride ion, F⁻,

<h3>The formula of the magnesium halide is MgF₂</h3>

6 0

3 years ago

A change resulting in one or more new substances being formed is a?

dem82 [27]

Answer:

C. Chemical change

Explanation:

A physical change is where something is changed but it doesnt affect the build up of the chemical. For example, if you broke sticks and threw them on the ground, that would be a physical change because the change is happening to the physical being of the object and not its chemical buildup. However, if you lit those sticks on fire, that would be considered a chemical change because you end up with two substances, ash and the remnants of the stick. A nuclear reaction would result in something blowing up so its not that. And a physical property is like what it looks like or how it smells. Hope I helped you!

3 0

3 years ago

Acts as the digestive system inside a cell. It helps to break down old or unneeded parts of the cell, and substances that have b

DIA [1.3K]

Answer:

I think it is enzymes

Explanation:

5 0

3 years ago

When light is shown on a mixture of chlorine and chloromethane, carbon tetrachloride is one of the components of the final react

velikii [3]

A free-radical substitution reaction is likely to be responsible for the observations. The reaction mechanism of a reaction like this can be grouped into three phases:

Initiation; the "light" on the mixture deliver sufficient amount of energy such that the halogen molecules undergo homologous fission. It typically takes ultraviolet radiation to initiate fissions of the bonds.
Propagation; free radicals react with molecules to produce new free radicals and molecules.
Termination; two free radicals combine and form covalent bonds to produce stable molecules. Note that it is possible for two carbon-containing free-radicals to combine, leading to the production of trace amounts of long carbon chains in the product.

Initiation

$\text{Cl}-\text{Cl} \stackrel{\text{UV}}{\to} \text{Cl}\bullet + \bullet\text{Cl}$