Why might it be important in a real life situation, to know if a chemical or physical change occurred?

1 answer:

6 0

There are four signs that a chemical reaction has occurred: a change in color, a change in temperature, formation of a gas or formation of a precipitate. A precipitate is a solid that forms when two liquid solutions are mixed. As matter changes in a chemical reaction, it can either absorb or release energy.

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Write net ionic equations for the formation of each of the precipitates observed. Express your answers as chemical equations sep

8090 [49]

answer is attached in image

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3 years ago

How many moles are in 2.12g Cr2O3

ohaa [14]

Answer:

0.01395mol Cr2O3

Explanation:

the molar mass of Cr2O3 is 151.9904 g/mol

2.12g Cr2O3 x 1 mol/151.9904g = 0.01395mol Cr2O3

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3 years ago

Which of the following pH numbers are basic? (Choose 2) 11 5 7 9

timama [110]

Answer:

7 is the only basic number on a pH scale

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kipiarov [429]

Density does not change with the amount of matter.

The density of water is 1 g/mL whether you have 1 mL or 1000 mL of water. Density is an intensive property.

Mass, volume, and weight change with the quantity of matter. For example, the mass of 1000 mL of water is greater than the mass of 1 mL of water. Mass, volume, and weight are extensive properties.

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3 years ago

When 1.0 mole of MgSO4 is dissolved in water contained in a calorimeter, the temperature of the water and dissolved ions increas

KatRina [158]

Answer: negative , from , to , exothermic

Explanation:

An endothermic reaction is a type of chemical reaction in which energy is absorbed from the surrounding. The temperature of the surrounding decreases.

An Exothermic reaction is a type of chemical reaction in which energy is released into the surrounding. The temperature of the surrounding increases.

Endothermic reactions are those in which heat is absorbed by the system from the surroundings and exothermic reactions are those in which heat is released by the system to the surroundings. $\Delta H$ for Endothermic reaction is positive and

As on dissolution of salt, the temperature of water increases, the heat has been released from system into surroundings and thus $\Delta H$ is negative.

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3 years ago