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hodyreva [135]
3 years ago
9

Which of the following substances is an element? A. carbon (C) B. water (H2O) C. methane (CH4) D. brass (Cu + Zn)

Chemistry
2 answers:
Sladkaya [172]3 years ago
8 0
The Answer is Carbon.
stealth61 [152]3 years ago
8 0
You answer is D. Brass
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) How many moles are there in 2.00 x 10^19 molecules of calcium phosphate?
Tamiku [17]

Answer:

\huge 3.322 \times  {10}^{ - 5}  \:  \: moles  \\

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

n =  \frac{N}{L} \\

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

n =  \frac{2.00 \times  {10}^{19} }{6.02 \times  {10}^{23} }  \\  \\  = 3.322 \times  {10}^{ - 5}  \:  \: moles

Hope this helps you

4 0
3 years ago
Chlorine pentafluoride gas is collected at -17.0 °C in an evacuated flask with measured volume of 35.0 L. When all the gas has b
Svet_ta [14]

Answer:

1. The mass of Chlorine pentafluoride, ClF5, is 39.16g

2. The number of mole of Chlorine pentafluoride, ClF5, is 0.3mole

Explanation:

1. To solve the mass of Chlorine pentafluoride, ClF5, first, let us calculate the molar mass of ClF5. This is illustrated below:

Molar Mass of ClF5 = 35.5 + (5 x 19) = 35.5 + 95 = 130.5g/mol

From the ideal gas equation:

PV = nRT (1)

Recall:

Number of mole(n) = mass (m) /Molar Mass(M)

n = m/M

Now substituting the value of n in equation 1, we have:

PV = nRT

PV = mRT/M

Now we can obtain the mass of Chlorine pentafluoride ClF5 as follow:

Data obtained from the question include:

T (temperature) = -17.0 °C = - 17 + 273 = 256K

V (volume) = 35L

P (pressure) = 0.180 atm

R (gas constant) = 0.082atm.L/Kmol

m (mass of Chlorine pentafluoride) =?

M (molar mass of Chlorine pentafluoride) = 130.5g/mol

PV = mRT/M

0.180 x 35 = m x 0.082 x 256/ 130.5

Cross multiply to express in linear form as shown below:

m x 0.082 x 256 = 0.180x35x130.5

Divide both side by 0.082 x 256

m = (0.180x35x130.5) /(0.082x256)

m = 39.16g

Therefore, the mass of Chlorine pentafluoride, ClF5, is 39.16g

2. The number of mole of ClF5 can be obtained as follow:

Mass of ClF5 = 39.16g

Molar Mass of ClF5 = 130.5g/mol

Mole of ClF5 =?

Number of mole = Mass /Molar Mass

Mole of ClF5 = 39.16/130.5g

Mole of ClF5 = 0.3mole

8 0
4 years ago
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Chemical reactions are known as electron transfer reaction.
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