What phase change is a gas to solid

If 3.50 g of the unknown compound contained 0.117 mol of c and 0.233 mol of h, how many moles of oxygen, o, were in the sample?

makvit [3.9K]

To determine the amount of oxygen that is present in the compound, we have to assume that the given compound contains carbon, hydrogen and oxygen only or else we will not be able to determine the answer. We need to convert the moles of the elements given to units of grams by using the atomic mass of these elements. Then, from the total amount of the compound we subtract the masses of the elements. We do as follows:

mass
0.117 mol C ( 12.01 g / 1 mol ) = 1.41 g
0.233 mol H ( 1.01 g / 1 mol ) = 0.24 g

Mass O = 3.50 g - 1.41 g - 0.24 g = 1.85 g O
Moles O = 1.85 g O ( 1 mol / 16 g ) = 0.116 moles O

6 0

3 years ago

Calcium has a cubic closest packed structure (fcc) as a solid. Assuming that calcium has an atomic radius of 197 pm, calculate t

Paha777 [63]

Answer:

$1.536 g/cm^3$ is the density of solid calcium.

Explanation:

Formula used :

$\rho=\frac{Z\times M}{N_{A}\times a^{3}}$

where,

$\rho$ = density

Z = number of atom in unit cell

M = atomic mass

$(N_{A})$ = Avogadro's number

a = edge length of unit cell

We have:

r = 197 pm = $197\times 10^{-12} m = 197\times 10^{-12}\times 100 cm$

$r=197\times 10^{-10} m$

$a=r\times 2\sqrt{2}$

$a=197\times 10^{-10} m\times 2\sqrt{2}=557.200\times 10^{-10} cm$

M = 40 g/mol

Z = 4

On substituting all the given values , we will get the value of 'a'.

$\rho =\frac{4\times 40 g/mol}{6.022\times 10^{23} mol^{-1}\times (557.200\times 10^{-10} cm)^{3}}$

$\rho =1.536 g/cm^3$

$1.536 g/cm^3$ is the density of solid calcium.

5 0

3 years ago

How do scientist know that atoms and molecules combine in well-ordered arrays?

xxTIMURxx [149]

They have microscopes to see small objects such as atoms and molecules

7 0

4 years ago

What happens when an electron absorbs energy? A. The electron moves from a lower energy orbital to a higher energy orbital. B. T

djyliett [7]

A. The electron moves from a lower to a higher energy orbital

7 0

3 years ago

Read 2 more answers

Objective (3 points)

velikii [3]

Answer:

Skilled Scientist level from Rubric: The student clearly explained the purpose of the lab, showing critical thinking skills.

Procedure:

Investigate each of the three components of cell theory to investigate from the corkboard in the virtual lab:

All organisms are composed of cells.

Cells come from existing cells.

Cells are the basic unit of life.

For each section, record your observations below.

Complete your report and submit it for grading.Data and Observations (27 points):

Skilled Scientist level from Rubric: Data and/or observations were recorded accurately for each section; observations include important details, such as observable detail when appropriate.

Investigation #1 (9 points): All organisms are composed of cells.

What is the main function of each part of the compound microscope? Explain in your own words using information from the activity on page 7 of the lesson.

Part

FunctionEye piece

Ocular lens

Objective lenses

Slide

Cover slip

Stage

Focusing dials

Light

Condenser lens

Observe each specimen under the microscope, and record a description about its appearance.

HINT: What do you see with youreyes? Describe the colors, shapes and how the cells are spaced.

Specimen Type

Description

Plant cell

Animal cell

Bacteria cell

Investigation #2 (9 points): Cells come from existing cells.

Observe the two flasks, and record information about their appearance.

HINT: What do you see with your eyes? If nothing has changed write “no change”

Day

Flask with open (broken) neck

Flask with intact neck

1

24

5

Investigation #3 (9 points): Cells are the basic unit of life.

Observe the two petri dishes, and record information about their appearance.

Day

Petri dish (on left) containing agar plus nutrients

Petri dish (on right) containing agar without nutrients

1

2

3

4

5

Conclusion :

Use your data to answer the following questions in your own words. Use complete sentences, and be as detailed as possible.

Skilled Scientist level from Rubric: The student demonstrated excellent critical thinking and problem solving skills when answering the conclusion questions. Answers and ideas were expanded with unique details that were novel and showed creative thinking.

How did scientists discover that all living things are made of cells?

HINT: Review Investigation #1 for on this question.

How did Pasteur’s experiment with the flasks disprove the idea that living things could just appear or come from nonliving things like water and air?

HINT: Review Investigation #2 for on this question.

Why are nutrients needed for living things? Describe the difference between living and nonliving things.

HINT: Review Investigation #3 for on this question.

TO SUBMIT YOUR COMPLETED FILE FOR GRADING:

can you

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