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3 years ago

What methods do scientists use to determine if a change was physical or chemical?

1 answer:

5 0

A physical change will not change the chemical make-up of the material. the change will not produce a new substance.

a chemical change will have a reaction that produces heat, light, a change in color, releases a gas, or rust

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The enthalpy of combustion for octane (C8H18(l)), a key component of gasoline, is -5,074 kJ/mol. This value is the Delta. Hrxn f

Inessa [10]

Combustion can be defined as the reaction of a compound with oxygen. The enthalpy of combustion of octane is $\Delta H_{\rm rxn}$ for $\rm C_8H_{18}\;+\;25\;O_2\;\rightarrow 8\;CO_2\;+\;9\;H_2O$ .

<h3>What is the enthalpy of reaction?</h3>

The enthalpy of reaction is the amount of heat energy absorbed or lost by the molecules in the chemical reaction.

The enthalpy of combustion is the amount of heat energy released by the compound in the reaction with oxygen.

The reaction in which heat is liberated with the reaction of a compound with oxygen has an enthalpy of combustion, equivalent to the enthalpy of reaction.

The combustion of octane can be given as:

$\rm C_8H_{18}\;+\;25\;O_2\;\rightarrow 8\;CO_2\;+\;9\;H_2O$

Thus, the reaction has combustion energy equivalent to the enthalpy of the reaction is $\rm C_8H_{18}\;+\;25\;O_2\;\rightarrow 8\;CO_2\;+\;9\;H_2O$ . Thus, option B is correct.

Learn more about enthalpy of reaction, here:

brainly.com/question/1657608

6 0

3 years ago

What is the Electron Center Geometry of a CH3 carbon.

wel

Answer:

tetrahedral geometry

Explanation:

There are several centers of interest. Each carbon with all single bonds is the center of a tetrahedral geometry.

6 0

3 years ago

Which one of the following groups of chemical compounds is composed entirely of organic compounds?

guajiro [1.7K]

Answer:

Explanation:

Organic compounds are chemical compounds which usually contains one or more atoms of carbon, hydrogen, oxygen and sometimes nitrogen or sulphur. Carbon and hydrogen are the main element that is contained in most organic compounds.

Option A is wrong because calcium phosphate is not an organic compound, although all the other compounds in the option are organic compounds.

Option B is wrong because calcium chloride is not an organic compound

Option C is wrong also as calcium sulphate is not an organic compound

Option D is correct as all are organic compounds

7 0

3 years ago

As the elements are considered from left to right in period 4 which is the correct sequencing of the elements?

velikii [3]

https://quizlet.com/17797282/periodicity-review-flash-cards/

i took a test like this and i went to this site /\ /\ /\ and the flash cards have the answers

8 0

3 years ago

To what extent do covalent compounds conduct electricity?

sertanlavr [38]

The answer is never because there's no electricity

3 0

3 years ago

Read 2 more answers