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3 years ago

15

Which term refers to the movement of materials through a cell membrane when the cell’s energy is required?

A) active transport B) passive transport C) diffusion D) osmosis

1 answer:

Mumz [18]3 years ago

6 0

The answer to this is A.

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Select all that apply to physical and chemical properties ?

MaRussiya [10]

Answer:

• Chemical properties can only be observed during a chemical reaction:

Chemical properties can only be established by changing a substance's chemical identity, and chemical properties are different from physical properties, which can be observed by viewing or touching a sample. The internal qualities of a substance must be altered to determine its chemical properties.

Examples:

Some common chemical properties are heat of combustion, enthalpy of formation, toxicity,

and flammability, each of which will be covered in this lesson.

• Rusting of iron is the chemical reaction not physical because:

The rusting of iron is a chemical change because it is two substances reacting together to make a

new substance. When iron rusts, iron molecules react with oxygen molecules to make a compound

called iron oxide. Rusting would only be a physical change if iron molecules remained pure iron

throughout the process.

The equation for this reaction is: 4Fe+ 3O2 → 2Fe2O

• Melting and boiling points are physical properties:

Yes melting and boiling points are the physical properties.

Physical properties can be observed or measured without changing the composition of matter. Physical properties are used to observe and describe matter.

Physical properties include: appearance, texture, color, odor, melting point, boiling point, density, solubility, polarity, and many others.

• Mass and volume are chemical properties:

No mass and volume are the extensive physical properties of matter

All properties of matter are either physical or chemical properties and physical properties are either intensive or extensive.

Extensive properties, such as mass and volume, depend on the amount of matter being measured.

Intensive properties, such as density and color, do not depend on the amount of the substance present.

Physical properties can be measured without changing a substance’s chemical identity.

• Various components of a mixture do not combine chemically:

When various components of a mixture do not combine chemically it is a Combination of substances in which individual components do not combine chemically but retain their individual properties. Mixture in which one or more substances are distributed evenly in another substance.

When various components combine chemically then form chemical compounds that are often divided into two categories. Metals often react with nonmetals to form ionic compounds. These compounds are composed of positive and negative ions formed by adding or subtracting electrons from neutral atoms and molecules

7 0

3 years ago

Read 2 more answers

How has thermal energy, heat, and temperature change?

maria [59]

thermal energy leads to an increase in the kinetic energy also increasing in temperature hope this helped!

3 0

3 years ago

Read 2 more answers

How can equilibrium of a closed system chemical reaction be disturbed? Select all that apply.

charle [14.2K]

The correct answers are :

Changing the volume of the system.

Changing the temperature of the system.

Equilibrium will remain unaffected if the concentration of products and reactants are kept the same, and the temperature of the system is kept constant.

As the system is closed, we cannot add or remove products or reactants.

Change in temperature will shift the chemical equilibrium towards the reactant or product depending on whether the reaction is exothermic or endothermic.

Also change in volume will shift the chemical equilibrium of a chemical reaction if the reactants or products or both are gases.

8 0

3 years ago

Read 2 more answers

A gaseous compound is 30.4 % N and 69.6% OF. A 5.25 g sample of the gas occupies a volume of 1.00 L and exerts a pressure of 958

Harman [31]

Answer:

The molecular formula = N2O4

Explanation:

<u>Step 1</u>: Data given

A gaseous compound is 30.4 % N and 69.6%

Mass of the compound = 5.25 grams

Volume of the gas = 1.00 L

Pressure of the gas = 958 mmHg = 1.26 atm

Temperature of the gas = -4 °C = 273 -4°C = 269 Kelvin

Molar mass of N = 14 g/mol

Molar mass of O = 16 g/mol

<u>Step 2</u>: Calculate mass of N

Mass of Nitrogen = 5.25 grams * 0.304 = 1.596 grams

<u>Step 3:</u> Calculate mass of O

Mass of Oxygen = 5.25 grams * 0.696 = 3.654 grams

<u>Step 4:</u> Calculate number of moles N

Number of moles N = Mass of N/ Molar mass of N

Moles of N = 1.596 grams / 14g/mol

Moles of N = 0.114 moles N

<u>Step 5:</u> Calculate moles of O

Moles O = 3.654 grams / 16 g/mol

Moles 0 = 0.2884 moles

<u>Step 6:</u> Calculate empirical formule

We calculate the empirical formule by dividing number of moles by the smallest number of mol

N : 0.114 / 0.114 = 1

O: 0.2284 / 0.114 = 2

Empirical formule = NO2

<u>Step 7: </u>Calculate number of moles of 5.25 g sample via gas law:

p*V = nRT

⇒ with p = the pressure = 1.26 atm

⇒ with v = 1.00 L

⇒ with n = the number of moles = TO BE DETERMINED

⇒ with R = the gas constant = 0.08206 L*atm/ K*mol

⇒ with T = the temperature = 269 K

number of moles n = (p*V)/(R*T)

n = (1.26*1L)/(0.08206*269)

n = 0.057 mol

<u>Step 8:</u> Calculate molar mass of the compound

This means 5.25 grams of the gas = 0.057 moles

So 1 mol of the compound has a molar mass of: 5.25 / 0.057 = 92.11 g/mol

<u>Step 9</u>: Calculate molar mass of the empirical formula NO2

N = 14 g/mol

O = 16 g/mol

NO2 = 14 + 16 + 16 = 46 g/mol

The empirical formule NO2 has a molar mass of 46 g/mol

<u>Step 10</u>: Calculate molecular formula

92.11 / 46 = 2

This means the empirical formula should be multiplied by 2

2*(NO2) = N2O4

The molecular formula = N2O4

8 0

3 years ago

When water reacts with potassium metal the hydrogen produced ignites explosively on the surface of water .What cause the ignitio

Julli [10]

Answer:

Pottasium reacts with water vigorously and the reation is exothermic. The heat released causes the hydrogen released to ignite

Explanation:

7 0

3 years ago