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PtichkaEL [24]
3 years ago
8

I have the stupid pls help

Chemistry
2 answers:
Black_prince [1.1K]3 years ago
6 0

Answer:

third sentences is correct i think

xenn [34]3 years ago
3 0

Answer:

combined number of protons and electrons

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Completely reacting 150.0 g of a substance with oxygen releases 395.1 J of energy. How much energy would be released if 450.0 g
MrMuchimi
To solve this problem we just need to use the rule of three:
150g..................395.1J
450g................xJ

x = 450*395.1/150 = 1185,3J

450.0 g of the substance completely reacted with oxygen will produce 1.1853 kJ(<span>kiloJoule</span>)
4 0
4 years ago
Read 2 more answers
Calculate the mass percent of Cl in Freon -112 (C2 Cl4 F2), a CFC refrigerant
Karolina [17]

Answer:

The answer to your question is:  69.6 %

Explanation:

Freon -112 (C₂Cl₄F₂)

MW = (12 x 2) + (35.5 x 4) + (19 x 2)

      = 24 + 142 + 38

      = 204 g

                       204 g of C₂Cl₄F₂  -----------------  100%

                       142 g                     -----------------   x

                      x = (142 x 100 ) / 204

                      x = 69.6 %

5 0
3 years ago
Read 2 more answers
Which temperatures originally represented the fixed points<br> Celsius temperature scale?
frez [133]

Answer:Since 1743 the Celsius scale has been based on 0 °C for the freezing point of water and 100 °C for the boiling point of water at 1 atm pressure. Prior to 1743 the values were reversed (i.e. the boiling point was 0 degrees and the freezing point was 100 degrees).

Explanation: i no it

8 0
3 years ago
A balloon filled with helium occupies 21.0ft³ at 55.0°F. Find the temperature of the helium if the volume of the balloon decreas
harkovskaia [24]

Answer:

Assuming pressure is held constant,the question reduces to a ratio and proportion type of question where;

At constant pressure,

21.0ft³-55.0°F

11.0fy³=11.0ft³/21.0ft³×55°F

The temperature is 28.809°F≈29°F

6 0
3 years ago
What are the key characteristics of a synthesis reaction
Crazy boy [7]

Answer is: There are more reactants and one product of the reaction. The reactants may be elements or compounds. The product is always a compound.

Synthesis reaction is a type of reaction in which multiple reactants combine to form a single product.

For example, balanced chemical reaction: Ba + F₂ → BaF₂.

In barium fluoride, barium has oxidation number +2 and fluorine has oxidation number -1, so compound has neutral charge.

Second chemical reaction: CaO(s) + H₂O(l) → Ca(OH)₂(aq).

One molecule is produced from two molecules.

8 0
3 years ago
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