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3 years ago

Which properties change the composition of a substance? A physical properties

Chemistry

2 answers:

Ugo [173]3 years ago

8 0

The correct answer is B.

Deffense [45]3 years ago

7 0

Answer:

chemical properties

Explanation:

chemical properties did change the composition of substance, so it cannot go back to original anymore, such as burning, rusting, etc.

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Learning Properties of Matter Quiz Unit 2 Lesson 11 Grade 8

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Consider the reaction N2(g) + 2O2(g)2NO2(g) Using standard thermodynamic data at 298K, calculate the entropy change for the surr

zysi [14]

<u>Answer:</u> The value of $\Delta S^o$ for the surrounding when given amount of nitrogen gas is reacted is 231.36 J/K

<u>Explanation:</u>

Entropy change is defined as the difference in entropy of all the product and the reactants each multiplied with their respective number of moles.

The equation used to calculate entropy change is of a reaction is:

$\Delta S^o_{rxn}=\sum [n\times \Delta S^o_{(product)}]-\sum [n\times \Delta S^o_{(reactant)}]$

For the given chemical reaction:

$N_2+2O_2\rightarrow 2NO_2$

The equation for the entropy change of the above reaction is:

$\Delta S^o_{rxn}=[(2\times \Delta S^o_{(NO_2(g))})]-[(1\times \Delta S^o_{(N_2(g))})+(2\times \Delta S^o_{(O_2(g))})]$

We are given:

$\Delta S^o_{(NO_2(g))}=240.06J/K.mol\\\Delta S^o_{(O_2)}=205.14J/K.mol\\\Delta S^o_{(N_2)}=191.61J/K.mol$

Putting values in above equation, we get:

$\Delta S^o_{rxn}=[(2\times (240.06))]-[(1\times (191.61))+(2\times (205.14))]\\\\\Delta S^o_{rxn}=-121.77J/K$

Entropy change of the surrounding = - (Entropy change of the system) = -(-121.77) J/K = 121.77 J/K

We are given:

Moles of nitrogen gas reacted = 1.90 moles

By Stoichiometry of the reaction:

When 1 mole of nitrogen gas is reacted, the entropy change of the surrounding will be 121.77 J/K

So, when 1.90 moles of nitrogen gas is reacted, the entropy change of the surrounding will be = $\frac{121.77}{1}\times 1.90=231.36 J/K$

Hence, the value of $\Delta S^o$ for the surrounding when given amount of nitrogen gas is reacted is 231.36 J/K

7 0

3 years ago

Which statement is true about the activity series? (5 points)

coldgirl [10]

Answer: Correct statements are given below:

1) In activity series elements are listed according to their reactivity.

2) Nuclear reaction in which low atomic nuclei fuse to form a heavier nucleus with the release of energy. Nuclear fusion reaction occurs in the sun.

3) C3H8 + 5O2 → 3CO2 + 4H2O is the example of a combustion reaction.

4) 2Fe + O2 → 2FeO is the example of synthesis reaction. In synthesis reaction is a type of reaction in which two reactants combine to form a single product.

3 0

3 years ago

Read 2 more answers

Why do you think the atomic number is basically represented by the number of protons and not the number of electrons?

Naya [18.7K]

Answer:

The atomic number equals the charge on the nucleus. It therefore also equals the number of protons in the nucleus and also equals numerically the number of electrons in the neutral atom. i think so, hope this helps you

Explanation:

6 0

3 years ago

Convert mass to moles for both reactants. (Round to 2 significant figures.)

shepuryov [24]

Mass = mr x moles
Mr of CuCl2 = ( 63.5) + ( 35.5 x 2) = 134.5
2.5 = 134.5 x moles
2.5 / 134.5 = moles
Moles = 0.019 (2DP)

0.25g of Al
Mr of Al = 27
0.25 = 27 x moles
0.25/ 27 = 0.0093 moles (2sf)

Hope this helps :)

6 0

3 years ago

Read 2 more answers

What’s the temperature at the boiling and freezing point of water in fanrenheit

Dominik [7]

Answer:

Boiling is 212* Freezing is 32*

Explanation:

It simple facts

5 0

3 years ago