4

The boiling point of a substance is tested. After 10 tests, the result is given as 37+/−3°C. Which conclusion can be drawn from

kenny6666 [7]

From the data obtained from the tests, the actual boiling point lies between 34°C and 40°C.

The boiling point of a substance is the temperature at which the pressure of the substance becomes equal to atmospheric pressure. Pure substances have a sharp boiling point while impure substances boil over a temperature range.

In this case, the boiling point of the substance after 10 tests is obtained as 37+/−3°C. This implies that the actual boiling point lies between 34°C and 40°C.

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7 0

3 years ago

A scientist studies the growth of plants in a laboratory. Which experimental procedure would provide evidence that

dusya [7]

The experimental procedure would provide evidence that plants need

nitrogen to grow is by

Identical plants are placed in two air-tight containers with sufficient exposure to sunlight.
One container has nitrogen gas, and the other has room air. The scientist measures plant growth

It is necessary to use identical plants during the experiment as plants have

different rates of nitrogen absorption from the soil. It should also be done in

air-tight containers called terrariums to prevent loss or contamination of the

gases with other elements/compounds.

The identical plants containing nitrogen and room air should both be

measured for the growth difference between them.

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7 0

3 years ago

II. Binding Forces A. Write a brief, one or two sentence, description of each binding force listed below. 1. London dispersion f

Leya [2.2K]

Answer:

All description is given in explanation.

Explanation:

Van der Waals forces:

It is the general term used to describe the attraction or repulsion between the molecules. Vander waals force consist of two types of forces:

1. London dispersion forces

2. Dipole-dipole forces

1. London dispersion forces:

These are the weakest intermolecular forces. These are the temporary because when the electrons of atoms come close together they create temporary dipole, one end of an atom where the electronic density is high is create negative pole while the other becomes positive . These forces are also called induce dipole- induce dipole interaction.

2. Dipole-dipole forces:

These are attractive forces , present between the molecules that are permanently polar. They are present between the positive end of one polar molecules and the negative end of the other polar molecule.

Hydrogen bonding:

It is the electrostatic attraction present between the atoms which are chemically bonded. The one atom is hydrogen while the other electronegative atoms are oxygen, nitrogen or flourine. This is weaker than covalent and ionic bond.

Ionic bond or electrostatic attraction:

It is the electrostatic attraction present between the oppositely charged ions. This is formed when an atom loses its electron and create positive charge and other atom accept its electron and create negative charge.

Hydrophobic interaction:

It is the interaction between the water and hydrophobic material. The hydrophobic materials are long chain carbon containing compound. These or insoluble in water.

Covalent bond:

These compounds are formed by the sharing of electrons between the atoms of same elements are between the different element's atoms. The covalent bond is less stronger than ionic bond so require less energy to break as compared to the energy require to break the ionic bond.

5 0

3 years ago

Find the number of moles in 1.00 x 1023 atoms of chromium.

IRISSAK [1]

Answer:

<h2>0.17 moles</h2>

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

$n = \frac{N}{L} \\$

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

We have

$n = \frac{1.00 \times {10}^{23} }{6.02 \times {10}^{23} } = \frac{1}{6.02} \\ = 0.166112$

We have the final answer as

<h3>0.17 moles</h3>

Hope this helps you

8 0

3 years ago

how many grams of calcium oxide will be produced in a closed vessel containing 20.0 kg of calcium and 20.0 kg of oxygen gas if t

sergejj [24]

Answer:

27984.1311 g

Explanation:

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

<u>For calcium :- </u>

Mass of calcium = 20.0 kg = 20000 g ( 1 kg = 1000 g )

Molar mass of calcium = 40.078 g/mol

Thus,

$Moles= \frac{20000\ g}{40.078\ g/mol}$

$Moles\ of\ calcium= 499.0269\ mol$

<u>For oxygen gas :- </u>

Mass of oxygen gas = 20.0 kg = 20000 g ( 1 kg = 1000 g )

Molar mass of oxygen gas = 31.999 g/mol

Thus,

$Moles= \frac{20000\ g}{31.999\ g/mol}$

$Moles\ of\ oxygen\ gas= 625.0195\ mol$

According to the given reaction:

$2Ca+O_2\rightarrow 2CaO$

2 moles of calcium reacts with 1 moles of oxygen gas

Also,

1 mole of calcium react with 1/2 mole of oxygen gas

So,

499.0269 mole of calcium react with $\frac{1}{2}\times 499.0269$ mole of oxygen gas

Moles of oxygen gas = 249.5135 moles

Available moles of oxygen gas = 625.0195 moles

Limiting reagent is the one which is present in small amount. Thus, calcium is limiting reagent.

The formation of the product is governed by the limiting reagent. So,

2 moles of calcium produces 2 moles of calcium oxide

So,

1 mole of calcium produces 1 mole of calcium oxide

Also,

499.0269 mole of calcium produces 499.0269 mole of calcium oxide

Moles of calcium oxide = 499.0269 moles

Molar mass of calcium oxide = 56.0774 g/mol

Mass of calcium oxide = Moles × Molar mass = 499.0269 × 56.0774 g = 27984.1311 g

<u>27984.1311 g of calcium oxide will be produced.</u>

8 0

4 years ago