List five ways you use chemistry at home or school ?

If a sample of air in a school container was heated, would the percentage of oxygen in the air increase, decrease, or remain unc

Viktor [21]

Answer:

increase

Explanation:

Let's suppose we have a sample of air in a closed container. We heat the container and we want to predict what would happen to the pressure.

According to Gay-Lussac's law, the pressure of a gas is directly proportional to its absolute temperature.

Thus, if we increased the temperature of the air by heating it, its pressure would increase.

If a sample of air in a closed container was heated, the total pressure of the air would increase.

5 0

3 years ago

Consider the following reaction:C2H4(g) + F2(g) -----------> C2H4F2(g) Delta H = -549 kJEstimate the carbon-fluorine bond ene

frutty [35]

Answer:

Bond energy of carbon-fluorine bond is 485 kJ/mol

Explanation:

Enthalpy change for a reaction, is given as:

$\Delta H_{rxn}=\sum [n_{i}\times (E_{bond})_{i}]-\sum [n_{j}\times (E_{bond})_{j}]$

Where $(E_{bond})_{i}$ and $(E_{bond})_{j}$ represents average bond energy in breaking "i" th bond and forming "j" th bond respectively. $n_{i}$ and $n_{j}$ are number of moles of bond break and form respectively.

In this reaction, one mol of C=C, four moles of C-H and one mol of F-F bonds are broken. One mol of C-C bond, four moles of C-H bonds and two moles of C-F bonds are formed

So, $-549kJ=(1mol\times 614kJ/mo)+(4mol\times E_{C-H})+(1mol\times 154kJ/mol)-(1mol\times 347kJ/mol)-(4mol\times E_{C-H})-(2mol\times E_{C-F})$

or, $-549kJ=(1mol\times 614kJ/mo)+(1mol\times 154kJ/mol)-(1mol\times 347kJ/mol)-(2mol\times E_{C-F})$

or, $E_{C-F}=485kJ/mol$

So bond energy of carbon-fluorine bond is 485 kJ/mol

8 0

3 years ago

A substance made of two or more elements chemically combined in a set ratio, or proportion, is called a ___.

snow_lady [41]

Hey there!

The correct answer to your question is a compound.

A substance of two or more elements chemically combined in a set ratio, or proportion, is called a compound.
This is because compounds are made of two or more elements. Table salt is an example of a compound because it is made up of the elements chlorine and sodium.

Hope this helps you.
Have a great day!

7 0

3 years ago

7th grade Science//POINTS AND BRAINLIEST...AND plz hurry... Function of Organelles- Give the functions of the listed organelles:

vova2212 [387]

Answer: Chloroplast - The organelles are only found in plant cells and some protists such as algae. ... Chloroplasts work to convert light energy of the Sun into sugars that can be used by cells. The entire process is called photosynthesis and it all depends on the little green chlorophyll molecules in each chloroplast.

Mitochondria - are known as the powerhouses of the cell. They are organelles that act like a digestive system which takes in nutrients, breaks them down, and creates energy rich molecules for the cell. The biochemical processes of the cell are known as cellular respiration.

The cell membrane- controls the movement of substances in and out of cells and organelles. In this way, it is selectively permeable to ions and organic molecules.

Cytoplasm - is present within the cell membrane of all cell types and contains all organelles and cell parts. Cytoplasm has various functions in the cell. ... Cytoplasm is responsible for giving a cell its shape. It helps to fill out the cell and keeps organelles in their place.

Nucleus - This organelle has two major functions: it stores the cell's hereditary material, or DNA, and it coordinates the cell's activities, which include growth, intermediary metabolism, protein synthesis, and reproduction (cell division). Only the cells of advanced organisms, known as eukaryotes, have a nucleus.

Ribosomes - are a cell structure that makes protein. Protein is needed for many cell functions such as repairing damage or directing chemical processes. Ribosomes can be found floating within the cytoplasm or attached to the endoplasmic reticulum. ... Proteins are an essential part of all cells.

Endoplasmic reticulum (ER) - in biology, a continuous membrane system that forms a series of flattened sacs within the cytoplasm of eukaryotic cells and serves multiple functions, being important particularly in the synthesis, folding, modification, and transport of proteins .

Vacuoles - are membrane-bound sacs within the cytoplasm of a cell that function in several different ways. In mature plant cells, vacuoles tend to be very large and are extremely important in providing structural support, as well as serving functions such as storage, waste disposal, protection, and growth.

Lysosome - Inside a cell, numerous organelles function to remove wastes. One of the key organelles involved in digestion and waste removal is the lysosome. Lysosomes are organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria.

Chromosomes - are the thread-like structure found in the nuclei of both animal and plant cells. They are made of protein and one molecule of deoxyribonucleic acid (DNA) Chromosomes are important to this process to ensure the DNA is accurately replicated.

The nucleolus - makes ribosomal subunits from proteins and ribosomal RNA, also known as rRNA. It then sends the subunits out to the rest of the cell where they combine into complete ribosomes. Ribosomes make proteins; therefore, the nucleolus plays a vital role in making proteins in the cell.

Vesicles - are small cellular containers that perform a variety of functions. They can be used to move molecules, secrete substances, digest materials, or regulate the pressure in the cell.

The cell wall - is the protective, semi-permeable outer layer of a plant cell. A major function of the cell wall is to give the cell strength and structure, and to filter molecules that pass in and out of the cell.

Took some time hope it helped !!! <3

Explanation:

6 0

3 years ago

A space air is at a temperature of 75 oF, and the relative humidity (RH) is 45%. Using calculations, find: (a) the partial press

earnstyle [38]

Answer:

A) Partial Pressure of dry air = 13.32 KPa

Partial Pressure of water vapour = 1.332 KPa

B) Humidity ratio; X = 0.0691

C) V_p = 0.8384 m³/Kg

Explanation:

A) We are given;

Temperature = 75°F

Relative Humidity = 45%

Now,to calculate the partial pressure, we will use the relationship;

Relative Humidity = (Partial Pressure/Vapour Pressure) × 100%

Making partial pressure the subject;

Partial Pressure = Relative Humidity × Vapour Pressure/100%

From the first table attached, at temperature of 75°F, the vapor pressure is 29.6 × 10^(-3) bar = 29.6 KPa

Thus;

Partial Pressure of dry air = (45 × 29.6)/100

Partial Pressure of dry air = 13.32 KPa

From online values, vapour pressure of water vapour at 75°F = 2.96 KPa

Thus;

Partial Pressure of water vapour = (45 × 2.96)/100 = 1.332 KPa

B) humidity ratio of moist air is given as;

X = 0.62198 pw / (pa - pw)

where;

pw = partial pressure of the water vapor in moist air

pa = atmospheric pressure of the moist air

Thus;

X = (0.62198 × 1.332)/(13.32 - 1.332)

X = 0.0691

C) Formula for moist air specific volume is;

V_p = (1 + (xRw/Ra) × RaT/p

Where;

V_p is specific volume

T is temperature = 75°F = 297.039 K

p is barometric pressure which in this case is standard sea level pressure = 101.325 KPa

pw is partial pressure of the water vapor in moist air = 1.332 KPa

Rw is individual gas constant for water = 0.4614 KJ/Kg.K

Ra is individual gas constant for air = 0.2869 KJ/Kg.K

V_p = (1 + (0.0691 * 0.4614/0.2869)) × 0.286.9 * 297.039/101.325

V_p = 0.8384 m³/Kg

6 0

3 years ago