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siniylev [52]
3 years ago
12

What does it mean to be an exothermic chemical reaction? a) Energy is released when no new substances are made. b) Energy is rel

eased when new substances are made. c) Energy is absorbed when no new substances are made. d) Energy is absoebed when new substances are made. e) None of the choices are correct.
Chemistry
1 answer:
mario62 [17]3 years ago
3 0

Answer:b

Explanation:

Energy is released to form the product

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D. Strontium is the right answer
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3 years ago
Will GIVE BRAINLIEST --A student makes a standard solution of potassium hydroxide by adding 14.555 g to 500.0 mL of water. Answe
leva [86]

Answer:

0.5188 M or 0.5188 mol/L

Explanation:

Concentration is calculated as <u>molarity</u>, which is the number of moles per litre.

***Molarity is represented by either "M" or "c" depending on your teacher. I will use "c".

The formula for molarity is:

c = \frac{n}{V}

n = moles (unit mol)

V = volume (unit L)

<u>Find the molar mass (M) of potassium hydroxide.</u>

M_{KOH} = \frac{39.098 g}{mol}+\frac{16.000 g}{mol}+\frac{1.008 g}{mol}

M_{KOH} = 56.106 \frac{g}{mol}

<u>Calculate the moles of potassium hydroxide.</u>

n_{KOH} = \frac{14.555 g}{1}*\frac{1mol}{56.106g}

n_{KOH} = 0.25941(9)mol

Carry one insignificant figure (shown in brackets).

<u>Convert the volume of water to litres.</u>

V = \frac{500.0mL}{1}*\frac{1L}{1000mL}

V = 0.5000L

Here, carrying an insignificant figure doesn't change the value.

<u>Calculate the concentration.</u>

c = \frac{n}{V}

c = \frac{0.25941(9)mol}{0.5000 L}              

c = 0.5188(3) \frac{mol}{L}         <= Keep an insignificant figure for rounding

c = 0.5188 \frac{mol}{L}              <= Rounded up

c = 0.5188M               <= You use the unit "M" instead of "mol/L"

The concentration of this standard solution is 0.5188 M.

7 0
3 years ago
Which of these can be classified as a pure substance? Help please
saw5 [17]

Answer: The answer is salt

4 0
3 years ago
Read 2 more answers
Ep-15 why is carbon monoxide especially dangerous?
Rzqust [24]

Carbon monoxide is dangerous because it binds with hemoglobin in the blood.


Hemoglobin is made up of proteins that bind to iron atoms. The structure of the protein facilitates loose binding of oxygen. On other hand, Carbon monoxide binds very strongly to the iron in hemoglobin. Once carbon monoxide is bonded to hemoglobin, it is very difficult to release. This, eventually results in  blood losing it its ability to transport oxygen. Hence, the person will suffocate. Due to this, CO is dangerous. 

8 0
3 years ago
A total of 5 mol iron oxide has a mass of (798.5g)
Anit [1.1K]

Answer:

Yes , 5 mole of Iron Oxide has mass of  798.5 g

Explanation:

Formula of iron oxide:

Fe_{2}O_{3}

Atomic mass of Fe = 55.84 amu

Atomic mass of O = 15.99 amu

Molar mass of Fe2O3 = 2(atomic mass of Fe) + 3(atomic mass of O)

= 2(55.84) + 3(15.99)

=111.68 + 47.97

= 159.69 g/mol

<u>Molar mass</u> always equal to <u>1 mole</u> of the substance.

1 mole = 159.69 g

5 mole =

=5\times159.69

= 798.45 g

6 0
3 years ago
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