All categories

3 years ago

PLEASE. Arrange from highest to lowest highest melting point; NaCl, MgO, KBr, RbI. Explain your rationale.

Chemistry

1 answer:

Dmitry [639]3 years ago

8 0

Answer:

MgO> NaCl > KBr >RbI

Explanation:

Lattice energy refers to a measure of the energy contained in the crystal lattice of a compound. It is equal to the energy that would be released if the component ions were brought together from infinity. It is also defined as a measure of the energy released when ions are combined to make a compound or a measure of the cohesive forces that bind ions together in an ionic solid.

Melting points of ionic substances depend on their relative lattice energies. Similarly, the lattice energy depends on the size of the ions in the ionic solid. The smaller the sizes of the component ions, the greater the lattice energy. It can be seen that the sizes of cations and anions decrease steadily from RbI to MgO hence the lattice energy and melting point of the ionic solids increases in the order shown in the answer. The smaller the component ions in the lattice the greater the melting point of that ionic solid.

You might be interested in

When weak acids react with strong bases, the H+ from the weak acid is transferred to the:

frosja888 [35]

It teacts with OH and makes water and salt

5 0

3 years ago

A chemical reaction produces formaldehyde, with a chemical formula of CH2O. Carbon is in group 4A, Oxygen is in group 6A, and Hy

steposvetlana [31]

Answer:

Explanation:

carbon in group 4A needs 4 more electrons to be stable

hydrogen in group 1A has one electron needs 1 more t o be stale

oxygen in group 6A has 6 and needs 2 more to be stable

They all obtain this by sharing electrons 8 around C &O, 2 around H

H : C: H

:O:

5 0

2 years ago

Hydrocarbons do not dissolve in concentrated sulfuric acid, but methyl benzoate does. Explain this difference and write an equat

finlep [7]

Answer:

See explanation

Explanation:

For a substance to dissolve in another, there must be some sort of interaction between the substances.

Recall that like dissolves like. That is, polar substances dissolve polar substances and non polar substances dissolve nonpolar substances.

Hydrocarbons are nonpolar hence they do not dissolve in polar sulphuric acid. Methyl benzoate is polar hence it dissolve in polar sulphuric acid.

The equation showing the ions is depicted in the image attached to this answer.

7 0

2 years ago

Which of the following would be SI unit to use in measuring the temperature of hot liquid

Vinil7 [7]

The unit is the Kelvin, but most of the time 273 is subtracted from the Kelvin temperature and the new number is called "degrees Celsius".

4 0

3 years ago

Read 2 more answers

John dissolves .5g of a white powder in 25g of benzene (FP 5oC) (kf benzene is 5.1) and finds the solution freezes at 3.7oC. Det

navik [9.2K]

Answer:

The compound has a molar mass of 78.4 g/mol

Explanation:

Step 1: data given

Mass of a sample = 0.5 grams

Mass of benzene = 25 grams

Freezing poing = 5 °C

Kf of benzene = 5.1 °C/m

Freezing point solution = 3.7 °C

Step 2: Calculate molality

ΔT = i*Kf*m

⇒with ΔT = the freezing point depression = 5.0 - 3.7 = 1.3 °C

⇒with i = the can't hoff factor = 1

⇒with Kf = the freezing point depression constant of benzene = 5.1 °C/m

⇒with m = the molality

1.3 = 5.1 * m

m = 1.3 / 5.1

m = 0.255 moles /kg

Step 3: Calculate moles

Molality = moles / mass benzene

0.255 molal = moles / 0.025 kg

Moles = 0.255 molal * 0.025 kg

Moles = 0.006375 moles

Step 4: Calculate molar mass of the compound

Molar mass compund = mass / moles

Molar mass compound = 0.5 grams / 0.006375 moles

Molar mass compound = 78.4 g/mol

The compound has a molar mass of 78.4 g/mol

7 0

2 years ago