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swat32
3 years ago
13

is there a relationship between the relative age of stars in the number/identity of element is found within them

Chemistry
1 answer:
lukranit [14]3 years ago
8 0

Yes. Stars use fusion to create nuclear energy, which is what makes them "alive". The older they are, the "bigger" the element in them is. Hydrogen turns into Helium, and when hydrogen is used up, the helium starts fusing into bigger elements. it stops at iron however. Once stars start fusing silicon to iron, it is doomed because it takes more energy than it gives off.

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3.
Katena32 [7]

Answer:

it's A endothermic its when two objects rub each other to form heat this is also known as friction force

6 0
3 years ago
7) What is the hydrogen concentration of a solution with a pH of 2.1? *
lesya [120]

Answer:

Hydrogen concentration = 7.94×10^-3 M

Explanation:

from potenz Hydrogen ( pH ) definition

pH = -log[H+]

2.1 = -log[H+]

2.1/-log = -log[H+]/-log

10^-2.1 = [H+]

[H+] = 7.94×10^-3M

8 0
3 years ago
What concentrations of acetic acid (pKa = 4.76) and acetate would be required to prepare a 0.15 M buffer solution at pH 5.0? Not
Leni [432]

Answer:

Acetic acid 0,055M and acetate 0,095M.

Explanation:

It is possible to prepare a 0,15M buffer of acetic acid/acetate at pH 5,0 using Henderson-Hasselblach formula, thus:

pH = pka + log₁₀ [A⁻]/[HA] <em>-Where A⁻ is acetate ion and HA is acetic acid-</em>

Replacing:

5,0 = 4,76 + log₁₀ [A⁻]/[HA]

<em>1,7378 =  [A⁻]/[HA] </em><em>(1)</em>

As concentration of buffer is 0,15M, it is possible to write:

<em>[A⁻] + [HA] = 0,15M </em><em>(2)</em>

Replacing (1) in (2):

1,7378[HA] + [HA] = 0,15M

2,7378[HA] = 0,15M

[HA] = 0,055M

Thus, [A⁻] = 0,095M

That means you need <em>acetic acid 0,055M</em> and <em>acetate 0,095M</em> to obtain the buffer you need.

i hope it helps!

7 0
3 years ago
In a chemical equation the sum of the masses
monitta
The sum of the masses of the reactants must equal the sum of the masses of the products; as required by 
the Principle of Conservation of Mass. 
5 0
3 years ago
Sorry if it is blurry
Zina [86]
I really cant read it sorry i tried
7 0
3 years ago
Read 2 more answers
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