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stich3 [128]
3 years ago
14

Which substance can not be decomposed by a chemical change?

Chemistry
2 answers:
Dvinal [7]3 years ago
7 0
Copper. It's copper because it is an element, not a compound substance, so its already in its basic chemical form ^u^
max2010maxim [7]3 years ago
5 0
B. Copper since the rest of the choices are compounds. Copper is an element.
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A cylinder with a moving piston expands from an initial volume of 0.250 L against an external pressure of 2.00 atm. The expansio
kondor19780726 [428]

Answer:

The final volume of the cylinder is 1.67 L

Explanation:

Step 1: Data given

Initial volume = 0.250 L

external pressure = 2.00 atm

Expansion does 288 J of work on the surroundings

Step 2: Definition of reversible work:

Wrev = -P(V2-V1) = -288 J

The gas did work, so V2>V1  (volume expands) and the work has a negative sign.(Wrev<0)

V2 = (-Wrev/P)  + V1

⇒ with Wrev = reverse work (in J)

⇒ with P = the external pressure (in atm)

⇒ with V1 = the initial volume

We can see that your pressure is in  atm  and energy in J

To convert from J to L * atm we should use a convenient conversion unit using the universal gas constants :

R = 8.314472 J/mol *K and R= 0.08206 L*atm/K*mol

V2 =- (-288 J * (0.08206 L*atm/K*mol  /8.314 J/mol *K))/2.00 atm  + 0.250L

V2 = 1.67 L

The final volume of the cylinder is 1.67 L

8 0
3 years ago
Three common gaseous compounds of nitrogen and oxygen of different elementary composition are known: (A) laughing gas containing
Ede4ka [16]

Answer:

Please find how these data prove the law of multiple proportions below

Explanation:

The law of multiple proportions was proposed by an English chemist called John Dalton. The law states that when two elements combine and to form more than one compound. The weights/masses of the second element in the two compounds, which combines with a fixed ratio of the first element, is in a simple whole number ratio.

In this question, Nitrogen is said to combine with oxygen to give three different compounds as follows:

A) laughing gas containing 63.65% nitrogen i.e. 0.6365g

This means that the mass of oxygen will be (1-0.6365) = 0.3635g

B) colorless gas containing 46.68% nitrogen i.e. 0.4668g

This means that the mass of oxygen will be 0.5332g

C) brown toxic gas containing 30.45% nitrogen i.e. 0.3045g

This means that the mass of oxygen will be 0.6955g

The ratios of oxygen in the three compounds is therefore:

0.3635: 0.5332: 0.6955

Divide this ratio by the smallest number (0.3635)

0.3635/0.3635 = 1

0.5332/0.3635 = 1.467

0.6955/0.3635 = 1.913

Multiply this ratio by 2, we have:

2: 2.9 : 3.8

Hence, the simple whole number ratio is 2:3:4.

This proves the law of multiple proportions that oxygen is in simple whole number ratio in the three different compounds.

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3 years ago
Select the correct answer. When an atom in a reactant loses electrons, what happens to its oxidation number? A. Its oxidation nu
vfiekz [6]

Answer:

C. Its oxidation number increases.

Explanation:

  • <em><u>Oxidation is defined as the loss of electrons by an atom while reduction is the gain of electrons by an atom</u></em>.
  • Atoms of elements have an oxidation number of Zero in their elemental state.
  • When an atom looses electrons it undergoes oxidation and its oxidation number increases.
  • For example, <em><u>an atom of sodium (Na) at its elemental state has an oxidation number of 0. When the sodium atom looses an electrons it becomes a cation, Na+, with an oxidation number of +1 , the loss of electron shows an increase in oxidation number from 0 to +1.</u></em>
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3 years ago
Read 2 more answers
suppose you want to do an experiment to hear how three different objects would sound when you dropping them the same distance. y
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The variable would be the distance you dropped them.

8 0
4 years ago
PLZ HELP I WILL GIVE BRAINLISTS TO RIGHT ANSWER
galina1969 [7]
..........The answer is B
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