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3 years ago

An example of a change of state is __________. *

2 answers:

7 0

Changes of state are physical changes in matter. They are reversible changes that do not change matter's chemical makeup or chemical properties. For example, when fog changes to water vapor, it is still water and can change back to liquid water again.please mark brainliest if correct

NeX [460]3 years ago

3 0

Answer:

ice cube melting

Explanation:

bcoz it's a chemical change

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Calculate Delta G for each reaction using Delta Gf values: answer kJ ...thank you

Leni [432]

Answer:

a) $\Delta G=2.6kJ$

b) $\Delta G=-979.57kJ$

c) $\Delta G=264.21kJ$

Explanation:

Hello,

In this case, in each reaction we must subtract the Gibbs free energy of formation the reactants to the Gibbs free energy of formation of the products considering each species stoichiometric coefficients. In such a way, the Gibbs free energy of formations are:

$\Delta _fG_{H_2}=\Delta _fG_{I_2}=0kJ/mol\\\Delta _fG_{HI}=1.3kJ/mol\\\Delta _fG_{CO_2}=-394.4kJ/mol\\\Delta _fG_{CO}=-137.3 kJ/mol\\\Delta _fG_{NH_3}=16.7 kJ/mol\\\Delta _fG_{HCl}=-95.3kJ/mol\\\Delta _fG_{MnO_2}=465.37kJ/mol\\\Delta _fG_{Mn}=0kJ/mol\\\Delta _fG_{NH_4Cl}=-342.81kJ/mol$

So we proceed as follows:

$\Delta G=2\Delta _fG_{HI}-\Delta _fG_{H_2}-\Delta _fG_{I_2}\\\\\Delta G=2*1.3\\\\\Delta G=2.6kJ$

$\Delta G=\Delta _fG_{Mn}+2*\Delta _fG_{CO_2}-\Delta _fG_{MnO_2}-2*\Delta _fG_{CO}\\\\\Delta G=0+2*-394.4-465.37-2*-137.3\\\\\Delta G=-979.57kJ$

$\Delta G=\Delta _fG_{NH_3}+\Delta _fG_{HCl}-\Delta _fG_{NH_4Cl}\\\\\Delta G=16.7-95.3-(-342.81)\\\\\Delta G=264.21kJ$

Regards.

6 0

3 years ago

What is the molar mass of calcium carbonate (CaCO3) ?

agasfer [191]

Answer: 15.1 grams

Given reaction:

Na2CO3 + Ca(OH)2 → 2NaOH + CaCO3

Mass of Na2CO3 = 20.0 g

Molar mass of Na2CO3 = 105.985 g/mol

# moles of Na2CO3 = 20/105.985 = 0.1887 moles

Based on the reaction stoichiometry: 1 mole of Na2CO3 produces 2 moles of NaOH

# moles of NaOH produced = 0.1887*2 = 0.3774 moles

Molar mass of NaOH = 22.989 + 15.999 + 1.008 = 39.996 g/mol

Mass of NaOH produced = 0.3774*39.996 = 15.09 grams

Explanation:

6 0

3 years ago

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________ is isoelectronic with helium. ________ is isoelectronic with helium. li- b4+ be mg2+ b3+

Rashid [163]

B3+ is isoelectronic with helium.
Isoelectronicity is the phenomenon whereby two or more molecular entities have the same number of electrons or similar electronic configuration regardless of the nature of the elements that are involved.
In the question given above, helium and B3+ have the same number of electrons. Helium has two electrons. Boron has five electrons but it has given away three of the electrons [that is why it has a charge of +3] and it now has only two left.

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3 years ago

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What does the simplified model of the hall effect give for the density of free electrons in the unknown metal?

evablogger [386]

The simplified model of the hall effect proved that the current (electric) in metals are carried by electrons and not protons. The hall effect introduced the hall coefficient which is the ratio of the induced electric field to the current density x applied magnetic field. This coefficient is unique for each type of metal.

3 0

3 years ago

To demonstrate the formation of iron (iii) chloride from iron fillings

Pavel [41]

Iron (iii) chloride is obtained by vapor condensation from the reaction between chlorine gas and iron fillings.

<h3>How can iron (iii) chloride be formed from iron fillings?</h3>

Iron (ii) chloride can be formed from iron fillings in the laboratory as follows:

Iron fillings + Cl₂ → FeCl₃

Chlorine gas is introduced into a reaction vessel containing iron fillings and the iron (iii) chloride vapor formed is obtained by condensation.

In conclusion, iron (iii) chloride is formed by the the direct combination of iron fillings and chlorine gas.

Learn more about iron (iii) chloride at: brainly.com/question/14653649

#SPJ1

5 0

1 year ago