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3 years ago

Which of these processes indicates that smelting copper is a chemical change

Chemistry

2 answers:

BlackZzzverrR [31]3 years ago

5 0

The correct answer is D:

it involves breaking molecular bonds between copper compounds .

The explanation :

-when we melt a copper it is a physical change because the substance is still copper and have the same shape.

- but for example Burning a copper it is a chemical change. Fire activates a chemical reaction between copper and oxygen.

-The oxygen in the air reacts with the copper and the chemical bonds are broken.

- the chemical change is changing the other compound bonded to the copper atoms.

So, the correct answer is D

german3 years ago

4 0

<span>Answer is d. The material can be phsycal changes into a differnt shape or state (gas, liquid, solid) and its will still be essentially copper. A chemical change is changing what other elements or compound is bonded to the copper atoms</span>

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The six pollutants regulated under the Clear Air Act _____ between 1970 and 2001, while energy consumption increased 42 percent.

pochemuha

Answer:

increased only 6 percent

Explanation:

The six pollutants regulated under the Clear Air Act increased only 6 percent between 1970 and 2001, while energy consumption increased 42 percent.

7 0

3 years ago

Read 2 more answers

In which of the following is number of electrons the ion contains given correctly? A. H+ has 1 electron. B. Br- has 34 electrons

Leviafan [203]

The correct answer would be D. Ca^2+ has 18 electrons. This is because 2+ means that 2 electrons have been removed, and Ca starts out with 20 electrons. As 20 - 2 = 18 electrons, D is the correct answer.

Hope this helps!

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3 years ago

Read 2 more answers

Which of the following aqueous solutions has the lowest pH? Why?

jenyasd209 [6]

Answer:

HCI

Explanation:

The solution with the lowest pH is HCI with a pH value of 1. It is understood that it is more acidic because it is a strong acid.

6 0

3 years ago

How many moles are in a 12.0 g sample of NiC12

Nady [450]

Answer:

0.17 moles

Explanation:

In the elements of the periodic table, the atomic mass = molar mass. <u>Ex:</u> Atomic mass of Carbon is 12.01 amu which means molar mass of Carbon is also 12.01g/mol.

In order to find the # of moles in a 12 g sample of NiC-12, we will need to multiply the number of each atom by its molar mass and then add the masses of both Nickel and C-12 found in the periodic table:

Molar Mass of Ni (Nickel): 58.69 g/mol

Molar Mass of C (Carbon): 12.01 g/mol

Since there's just one atom of both Carbon and Nickel, we just add up the masses to find the molar mass of the whole compound of NiC-12.

58.69 g/mol of Nickel + 12.01 g/mol of Carbon = 70.7 g/mol of NiC-12

There's 12g of NiC-12, which is less than the molar mass of NiC-12, so the number of moles should be less than 1. In order to find the # of moles in NiC-12, we need to do some dimensional analysis:

12g NiC-12 (1 mol of NiC-12/70.7g NiC-12) = 0.17 mol of NiC-12
The grams cancel, leaving us with moles of NiC-12, so the answer is 0.17 moles of NiC-12 in a 12 g sample.

<em>P.S. C-12 or C12 just means that the Carbon atom has an atomic mass of 12amu and a molar mass of 12g/mol, or just regular carbon.</em>

5 0

3 years ago

When 4.088 grams of a hydrocarbon, CxHy, were burned in a combustion analysis apparatus, 13.82 grams of CO2 and 2.829 grams of H

yarga [219]

Answer:

Empirical formula: CH

Molecular formula: C₆H₆

Explanation:

Based on the combustion of a hydrocarbon, the moles of CO₂ = Moles of Carbon in the hydrocarbon and the moles of H₂O = 1/2 moles of hydrogen in the hydrocarbon.

The empirical formula is the simplest whole number of atoms present in a molecule. With the moles of C and H we can find empirical formula:

<em>Moles C -Molar mass CO₂ = 44.01g/mol-:</em>

13.82g * (1mol / 44.01g) = 0.314 moles C

<em>Moles H -Molar mass H₂O = 18.01g/mol-:</em>

2.829g H₂O * (1mol / 18.01g) = 0.157 moles H₂O * (2mol H / 1mol H₂O) = 0.314 moles of H

The ratio of moles H: moles C:

0.314 moles / 0.314 moles = 1

That means empirical formula is:

With the molecular weight and empirical formula we can find the molecular formula:

Molar mass CH = 12.01g/mol+1.01g/mol = 13.02g/mol

As the molecular weight of the molecule is 78.11amu = 78.11g/mol, there are:

78.11g/mol / 13.02g/mol = 6 times the empirical formula in the molecular formula

That means molecular formula is:

4 0

3 years ago