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Which of the following is a correct formula unit of an ionic compound?

goldenfox [79]

Answer : The correct formula unit of an ionic compound is Ca(OH)2

Explanation :

An ionic compound is formed when a metal atom donates one or more electrons to a non metal atom.

During this process, metal gains a positive charge and a nonmetal gets a negative charge.

In an ionic compound, these charges on the ions are balanced so that the overall compound is neutral.

Let us check which of the given compounds have a neutral charge.

1) Al2F3 : Charge on Al is +3 and that on F is -1.

The total charge on 2 Al is 2x3 = +6.

The total charge on 3 F atoms is 3x(-1) = -3

The overall charge on the compound is +6-3 = +3.

That means the given formula unit is not correct.

2) Ca2O : Charge on Ca is +2 and that on O is -2

Total charge on Ca is 2x2 = +4

The overall charge is +4-2 = +2

Therefore the given formula unit is not correct.

3) Ca(OH)2 : The charge on Ca ion is +2 and that on OH is -1.

The total charge on 2 OH ions is 2x(-1) = -2

The overall charge is +2-2 = 0

This gives a neutral compound.

Therefore the given formula unit is correct.

6 0

4 years ago

Read 2 more answers

Lastly, Snape thinks we should try one more calculation.

EleoNora [17]

Answer:

E) 0.90

Explanation:

In TLC (Thin-Layer-Chromatography) retention factor RF is defined as the ratio between distance of the sample and the solvent front. RF is very important in chemistry to know the composition of any sample by comparison.

In the problem, as the sample has a distance of 0,20cm from the solvent front, the distance of the sample is:

2,0cm - 0,20 cm = 1,8 cm. Thus, RF is:

RF = 1,8cm / 2,0cm = 0,90

E) 0,90

I hope it helps!

3 0

3 years ago

Balancing equations

Bad White [126]

Make sure you numbers with variable are on one side and the numbers

7 0

4 years ago

Which regions of the world seem to be suffering most from loss of species ?

Lana71 [14]

Answer:

The most dangerous area for animals and plants is the one that contains the greatest biodiversity on the planet: Southeast Asia. In this region are the five most affected countries in the world: Malaysia, Brunei, Singapore, Indonesia and Thailand. The Atlantic rainforests of Brazil are also very affected, this is due to the fact that great catastrophes have occurred in these places lately, such as the massive fire in the Amazon, and the floods that occurred after the tremendous absence of vegetation that these places suffered.

Explanation:

Also on the other hand, the regions with the highest extinction are those that carry out little environmental policies where care has not been taken for species that are in danger of extinction, as happens, for example, in those islands such as the Galapagos Islands, which are subject to severe fines for harm turtles.

3 0

3 years ago

Can somebody please help me with this question, I'm very confused! I thought i did it right because i found Kb and the conc. of

andrew-mc [135]

Let's investigate the substances involved in the reaction first. The compound CH3NH3+Cl- is a salt from the weak base CH3NH2 and the strong acid HCl. When this salt is hydrated with water, it will dissociate into CH3NH2Cl and H3O+:

CH3NH3+Cl- + H2O ⇒ CH3NH2Cl + H3O+

Nest, let's apply the ICE(Initial-Change-Equilibrium) table where x is denoted as the number of moles used up in the reaction:

CH3NH3+Cl- + H2O ⇒ CH3NH2Cl + H3O+
Initial 0.51 0 0
Change -x +x +x
-------------------------------------------------------------------------------
Equilibrium 0.51 - x x x

Then, let's find the equilibrium constant of the reaction. Since the reaction is hydrolysis we use KH, which is the ratio of Kw to Ka or Kb. Kw is the equilibrium constant for water hydrolysis which is equal to 1×10⁻¹⁴. Since the salt comes from the weak base, we use Kb. Since pKb = 3.44, then. 3.44 = -log(Kb). Thus, Kb = 3.6307×10⁻⁴

KH = Kw/Kb = (x)(x)/(0.51 - x)
1×10⁻¹⁴/ 3.6307×10⁻⁴ = x²/(0.51-x)
x = 3.748×10⁻⁶

Since x from the ICE table is equal to the equilibrium concentration of H+, we can find the pH of the aqueous solution:

pH = -log(H+) = -log(x)
pH = -log ( 3.748×10⁻⁶)
pH = 5.43

6 0

3 years ago