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enot [183]
3 years ago
5

Which of the following is a sign a chemical reaction has occurred?

Chemistry
2 answers:
tankabanditka [31]3 years ago
6 0
A solid dissolves in abolishing forms from the mixing of 2 liquids
dimulka [17.4K]3 years ago
6 0

Answer: A solid forms when two liquids are mixed.

Explanation:

A physical reaction is defined as the reaction in which a change in shape, size takes place. No new substance gets formed in these reactions.

A chemical reaction is defined as the reaction in which a change in chemical composition takes place. A new substance is formed in these reactions.

1. A solid dissolves in liquid: Only the phase of the solid changes to aqueous and no new substance is formed, thus is a physical change.

2. A solid forms when two liquids are mixed: two liquids can forma  solid only on chemical combination and formation of new substance.

3. A solid melts to a liquid when it is heated: Only the phase of the solid changes to liquid, no new substance is formed, thus is a physical change.

4. A solid metal changes shape: Only the shape of the solid changes, thus is a physical change.

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A gas has a volume of 6.35 L at 88.6 kPa. What will be the volume at standard pressure? Standard Pressure = 101.3 kPa
alukav5142 [94]

Answer:

5.55 L

Explanation:

This excersise can be solved by the Boyle's law.

This law for gases states that the pressure of a gas in a vessel is inversely proportional to the volume of the vessel.

P₁ . V₁  = P₂ . V₂

The law comes from the Ideal Gases Law, in the first term.

P . V = n . R . T  In this case, n . R . T are all constant.

6.35 L . 88.6 kPa = 101.3 kPa . V₂

V₂ = (6.35 L . 88.6 kPa) / 101.3 kPa

V₂ = 5.55 L

It is inversely proportional because, as it happened in this case, pressure was increased, therefore volume decreased.

5 0
3 years ago
Fireworks exploding in the sky and giving off light are an example of a(n) _____.
Serggg [28]
Exothermic change. Because the firework when it exploded, released energy in the form of light. In exothermic changes energy is released, and in endothermic changes energy is absorbed.

- This wouldn't be a physical change, but instead a chemical change. A clue that it is a chemical change is that energy was given off.
7 0
3 years ago
Read 2 more answers
Which of these elements is this group?
sergey [27]

Answer:

Strontium

Explanation:

In the periodic table, an element with two (2) valence electrons is found on group 2. Group 2 is a group of the periodic table that harbors element called ALKALINE EARTH METALS. As the name implies, they are metals that possess shiny and solid characteristics at room temperature.

Group 2 elements include the following: Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), barium (Ba), and radium (Ra). Based on the descriptive information in this question, the element being described is a GROUP 2 element. Based on the elements in the option, only STRONTIUM (Sr) is a group 2 element.

3 0
3 years ago
To what class of minerals do gold, silver, and copper belong?
Volgvan
Gold, Silver, Copper are all part of a class of minerals called Native Elements. Platinum, Graphite, Diamond and Mercury are also apart of this group. Also known as the Native Metals.
5 0
3 years ago
Word equation of nitrogen + oxygen —--> ammonia
katrin [286]

Answer:

it is ammonia nitro oxide

5 0
2 years ago
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