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boyakko [2]
2 years ago
5

Which of these is an example of a physical change?

Chemistry
1 answer:
vladimir2022 [97]2 years ago
6 0

Answer:

Their isn't your examples but I will give you mine

Freezing, Evaporation and so on.

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masya89 [10]
The answer is A.
A pure substance is pure, so it cannot be separated in most cases.
8 0
3 years ago
Mg(OH)2 + 2 HBr à MgBr2 + 2 H2O
AnnyKZ [126]

Explanation:

The balanced equation of the reaction is given as;

Mg(OH)2 (s) + 2 HBr (aq) → MgBr2 (aq) + 2 H2O (l)

1. How many grams of MgBr2 will be produced from 18.3 grams of HBr?

From the reaction;

2 mol of HBr produces 1 mol of  MgBr2

Converting to masses using;

Mass = Number of moles * Molar mass

Molar mass of HBr = 80.91 g/mol

Molar mass of MgBr2 = 184.113 g/mol

This means;

(2 * 80.91 = 161.82g) of HBr produces (1 * 184.113 = 184.113g) MgBr2

18.3g would produce x

161.82 = 184.113

18.3 = x

x = (184.113 * 18.3 ) / 161.82 = 20.8 g

2. How many moles of H2O will be produced from 18.3 grams of HBr?

Converting the mass to mol;

Number of moles = Mass / Molar mass = 18.3 / 80.91 = 0.226 mol

From the reaction;

2 mol of HBr produces 2 mol of H2O

0.226 mol would produce x

2 =2

0.226 = x

x = 0.226 * 2 / 2 = 0.226 mol

3. How many grams of Mg(OH)2 are needed to completely react with 18.3 grams of HBr?

From the reaction;

2 mol of HBr reacts with 1 mol of Mg(OH)2

18.3g of HBr =  0.226 mol

2 = 1

0.226 = x

x = 0.226 * 1 /2

x = 0.113 mol

5 0
2 years ago
What is the most appropriate unit of astronomical distance to represent the distance between an earth an orbiting space station
Reil [10]
Astronauts use "Astronomical Unit" to measure the distance between planets in our solar system "only". To measure long distances like between 2 galaxies, they use "light years". One Astronomical Unit = Average distance between sun and earth which is equal to 149.6 million kilometers. Ping me if you have any doubt.
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2 years ago
Which is produced in a synthesis reaction?
Rama09 [41]

Answer:

a single compound

Explanation:

which is produced in a synthesis reaction

5 0
2 years ago
Read 2 more answers
Why does energy spread out evenly if there's only a 21% chance that energy spreads out evenly?
Harrizon [31]

Answer:

It has to do with increasing the entropy of the universe.

Explanation:

The modern definition of entropy is that it is the extent to which a system is able to disperse its energy. Energy (such as heat!) likes to spread itself out, so that as many states as possible are occupied with the least amount of energy.

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