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3 years ago

How many potassium atoms are in 250.0 grams of potassium?

1 answer:

7 0

Use the atomic mass of potassium, k, 39.1 g/mol, and the formula n = mass / atomic-mass.

Where n is the number of moles.

n = 250.0 g / 39.1 g/mol = 6.3939 mol.

Now multiply by Avogadro number to find the number of atoms:

6.3939 mol * 6.02*1023 atoms/mol = 38.49 * 10^23 atoms = 3.849 * 10^24.

Answer: 3.85*10^24

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Consider the balanced equation for the following reaction:

Zanzabum

<u>Answer:</u> The amount of carbon dioxide formed in the reaction is 5.663 grams

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

Given mass of oxygen gas = 8 g

Molar mass of oxygen gas = 32 g/mol

Putting values in equation 1, we get:

$\text{Moles of oxygen gas}=\frac{8g}{32g/mol}=0.25mol$

For the given chemical equation:

$7O_2(g)+2C_2H_6(g)\rightarrow 4CO_2(g)+6H_2O(l)$

By Stoichiometry of the reaction:

7 moles of oxygen gas produces 4 moles of carbon dioxide

So, 0.25 moles of oxygen gas will produce = $\frac{4}{7}\times 0.25=0.143mol$ of carbon dioxide

Now, calculating the mass of carbon dioxide from equation 1, we get:

Molar mass of carbon dioxide = 44 g/mol

Moles of carbon dioxide = 0.143 moles

Putting values in equation 1, we get:

$0.143mol=\frac{\text{Mass of carbon dioxide}}{44g/mol}\\\\\text{Mass of carbon dioxide}=(0.143mol\times 44g/mol)=6.292g$

To calculate the experimental yield of carbon dioxide, we use the equation:

$\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100$

Percentage yield of carbon dioxide = 90 %

Theoretical yield of carbon dioxide = 6.292 g

Putting values in above equation, we get:

$90=\frac{\text{Experimental yield of carbon dioxide}}{6.292g}\times 100\\\\\text{Experimental yield of carbon dioxide}=\frac{90\times 6.292}{100}=5.663g$

Hence, the amount of carbon dioxide formed in the reaction is 5.663 grams

7 0

3 years ago

At 25◦C a 4 L sample of H2 exerts a pressure of 5 atm. What pressure would the same sample exert in a 2 L container at 25◦C?

kykrilka [37]

Answer:

10 atm.

Explanation:

Using the combined gas law equation as follows;

P1V1/T1 = P2V2/T2

Where;

P1 = initial pressure (atm)

P2 = final pressure (atm)

V1 = initial volume (L)

V2 = final volume (L)

T1 = initial temperature (K)

T2 = final temperature (K)

According to the information provided in this question,

P1 = 5 atm

P2 = ?

V1 = 4L

V2 = 2L

T1 = 25°C = 25 + 273 = 298K

T2 = 25°C = 298K

Using P1V1/T1 = P2V2/T2

5 × 4/298 = P2 × 2/298

20/298 = 2P2/298

Cross multiply

298 × 20 = 298 × 2P2

5960 = 596P2

P2 = 5960 ÷ 596

P2 = 10 atm.

4 0

3 years ago

How many significant figures are in the number 0.00230? O 6

EleoNora [17]

Answer:

0.00230 = <u>3 significant figures</u>

Explanation:

Significant digits or figures of a given number are the digits or figures that have meaning and contributes to the precision of the given number.

Therefore, <u>0.00230 = 3 significant figures.</u>

Reason: The non-zeros figures and the trailing zero after the decimal are significant. Whereas, all the leading zeros are not considered significant.

4 0

3 years ago

Aluminum reacts with chlorine gas to produce aluminum chloride according to the following equation. Al + Cl2 → AlCl3 Which of th

anzhelika [568]

<h3><u>Answer</u>;</h3>

B. 3/2

<h3><u> Explanation;</u></h3>

Balance the chemical equation

2Al + 3Cl2 → 2AlCl3

We want to convert moles of AlCl3 to moles of Cl2

The conversion factor is 2 mol AlCl3/3 mol Cl2.

We choose the one that makes the units cancel:

x mol AlCl3 x (3 mol Cl3)/(2mol AlCl3) = x mol Al

The fraction for the molar ratio is 3/2.

4 0

3 years ago

Read 2 more answers

Which of the following is the name of the process scientists use to gain

kobusy [5.1K]

Scientific method

Explanation:

The scientific method is the name of the process scientists use to gain knowledge about the physical world.

The scientific method is a systematic approach into the study of nature. It follows the following processes:

Detailed observation
Asking of question
Formulation of hypothesis
Experimentation
Analysis and interpretation
Conclusion

learn more:

Experiment brainly.com/question/1621519

#learnwithBrainly

8 0

4 years ago