The element boron, a trace element in earth's crust, is found in foods produced from plants. boron has only two naturally occurring stable isotopes, boron-10 and boron-11. one sample of a green vegetable contains 0.0035 gram of boron. determine the total number of moles of boron in this sample.

The answer to your question is: 0.00032 moles of Boron

Explanation:

Boron AM = 10.81 g

Mass = 0.0035 g in the sample

  Rule of three

                       10.81 g of Boron  1 mol

                       0.0035 g              x

                       x = (0.0035 x 1) / 10.81

                          = 0.00032 moles

Number of moles ≈ 0.000324 moles

Explanation:

The question is to calculate the number of moles in the sample.

We were given;

mass = 0.0035g

The relationship between mass and number of moles;

Mass = Number of moles * Molar Mass

Since the element occurs in isotopes, we have to calculate it''s average molar mass;

About 19.9% of all boron atoms are boron-10 with a mass of 10.0129 amu, and the remaining 80.1% are boron-11 with a mass of 11.0093 amu. The average atomic mass for boron is calculated to be:

boron average mass = (0.199×10.0129amu) + (0.801×11.0093amu)

= 1.99amu + 8.82amu = 10.81 amu

It is important to understand that no single boron atom weighs exactly 10.8 amu; 10.8 amu is the average mass of all boron atoms, and individual boron atoms weigh either approximately 10 amu or 11 amu.

Inserting back into the formular;

Number of moles = Mass / Molar mass

Number of moles = 0.0035 / 10.81

Number of moles = 0.000324 moles

Explanation:

What do gases consist of?

Gases consist of small particles that have mass.

What evidence does this reading give that gas particles have mass?

An inflated basket ball weighs more than a deflated basketball therefore, particles must have a mass.

Why can gases be compressed easily but not liquids and solids?

The gas molecules are separated from each other by relatively a large distance. The space between the particles allow them to be pushed closer together. Liquid and solids can not compressed easily because particles are packed tightly.

Why can gases filled their container completely but not solids?

The particles of gas must be on constant rapid motion. Because of this motion gases immediately fill their container. These rapid moving particle can mix easily with each other so that gas released at one end of container quickly diffuse to other end.

What is the collision?

The particles of gas are on constant rapid motion. Because of this motion gas molecules colloid with each other and also with the wall of container. When they strike with each other and with the wall this is called collision.

What does reading compare gas particles to?

This reading compare the gas particles with the rubber balls in a empty room.

According to reading how gas particles are differ from rubber balls?

The balls strike with each other and also with the wall and hence their motion slow down but in case of gas particles their motion can  not slow down on collision. Because of it is happens then gas convert in to the solid or liquid. That's why it is not happen in case of gas molecules.