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ANEK [815]
2 years ago
11

Why is copper a pure substance? a. because it is an element b. because it is a compund c. because it is a homogenous mixture

Chemistry
1 answer:
Step2247 [10]2 years ago
6 0

Answer:

a. because it is an element

Explanation:

its pure because it only has one type of atom, making it an element

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Juliette [100K]

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3 years ago
Steps to identify a mineral
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Http://www.geologyin.com/2014/11/how-to-identify-minerals-in-10-steps.html
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18. Which two particle diagrams each represent a sample of one substance? Key O = atom of oxygen = atom of hydrogen 0 = atom of
Mars2501 [29]

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1 and 11

Explanation:

3 0
3 years ago
A 0.133 pg sample of iron-59 produces 242 β-particles per second. what is the half-life of this isotope (in hours)
34kurt
1070 hours.  
1 mole of iron-59 would mass 59 grams, so 0.133 picograms would be 0.133x10^-12 / 59 = 2.25x10^-15 moles of iron-59. Multiplying by Avogadro's number, we can determine the number of atoms of iron-59 we have, so: 2.25x10^-15 * 6.02214x10^23 = 1.35x10^9 
 Since we have 242 decays over a period of 1 second, we can divide the
number of atoms left by the original number of atoms
 (1350000000 - 242)/1350000000
 = 1349999758/1350000000
 = 0.999999820740741 
 And calculate the logarithm to base 2 of that quotient.
 ln(0.999999820740741)/ln(2)
 = -1.79259275281191x10^-7/0.693147180559945
 = -2.58616467481524x10^-7 
 The reciprocal of this number will be the half life in seconds. So
 -1/2.58616467481524x10^-7
 = -3866729.79388461 
 And dividing by 3600 (number of seconds in an hour) will give the half-life in
hours.
 -3866729.79388461 / 3600 = -1074.091609 
 So the half life in hours to 3 significant figures is 1070 hours.
 Dividing that figure by 24 gives a half life of 44.58 days which is in pretty close agreement to the official half-life of 44.495 days for iron-59.

4 0
3 years ago
if kept at a constant temperature, what is the concentration at 865s if the initial concentration was 0.0225M
Anestetic [448]

Answer:

[SO_2Cl_2]=0.0175M

Explanation:

Hello!

In this case, considering that the decomposition reaction of SO2Cl2 is first-order, we can write the rate law shown below:

r=-k[SO_2Cl_2]

We also consider that the integrated rate law has been already reported as:

[SO_2Cl_2]=[SO_2Cl_2]_0exp(-kt)

Thus, by plugging in the initial concentration, rate constant and elapsed time we obtain:

[SO_2Cl_2]=0.0225Mexp(-2.90x10^{-4}s^{-1}*865s)

[SO_2Cl_2]=0.0175M

Best regards!

8 0
2 years ago
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