Giving brainless to who gets it correct

Some elements have variable valencies .give reason

Angelina_Jolie [31]

Answer:

Some elements have variable valencies because of the different electronic configurations. An atom of an element can sometimes lose more electrons than are present in its valence shell i.e. loss from the penultimate shell and hence exhibit more than 1 or variable valency.

Explanation:

Hope it helps.

3 0

3 years ago

The value of the equilibrium constant for a reaction

quester [9]

Answer:

a. changes with temperature.

Explanation:

Hello there!

In this case, according to the thermodynamic definition of the equilibrium constant in terms of the Gibbs free energy of reaction and the temperature of the system:

$lnK=-\frac{\Delta G}{RT}$

It is possible to figure out that the equilibrium constant varies as temperature does, not only on the aforementioned definition, but also in the Gibbs free energy as it is also temperature-dependent. Therefore, the appropriate answer is a. changes with temperature.

Best regards!

6 0

3 years ago

a 50.00-mL sample of bleach solution contains 0.214 M HClO and 0.667 M NaClO. The Ka of hypochlorous acid is 3.0 ✕ 10−8. Find th

amm1812

Answer:

A) pH = 8.11

B) pH = 7.96

Explanation:

The pH of buffer is calculated using Henderson Hassalbalch's equatio, which is

$pH=pKa+log\frac{[salt]}{[acid]}$

pKa = -logKa = -log(3.0 ✕ 10⁻⁸)

pKa = 7.5

[salt] = 0.667

[Acid] = 0.214

$pH = 7.5 + log\frac{0.667}{0.214}=7.99$

A) If the solution is halved it means the concentration of both salt and acid will be the same.

The volume will change

Number of moles of acid = molarity X volume = 0.214 X 25 = 5.35 mmol

Number of moles of salt = molarity X volume = 0.667 X 25 = 16.68 mmol

moles of NaOH added = molarity X volume = 0.100 X 10 = 1 mmol

These moles of NaOH will react with acid to give same amount of salt and thus the moles of acid will decrease

New moles of acid = 5.35 - 1 = 4.35

New moles of salt = 16.68 + 1 = 17.68

the new pH will be

$pH = 7.5 + log\frac{17.68}{4.35}=8.11$

B)

moles of HCl added = molarity X volume = 0.100 X 10 = 1 mmol

These moles of HCl will react with salt to give same amount of acid and thus the moles of salt will decrease

New moles of acid = 5.35 + 1 = 6.35

New moles of salt = 16.68 - 1 = 15.68

the new pH will be

$pH = 7.5 + log\frac{15.68}{5.35}=7.97$

3 0

3 years ago

4.0 L sample of methane gas is collected at 30.0c,<br> what is the volume of the sample at -8c?

Vedmedyk [2.9K]

This particular law is a gas law, called Charle's Law. The formula is:

V1 V2
---- = ----
T1 T2

So we know our original volume is 4.0L, so we would plug that into our V1. We know T1 is the 30 degrees, since it relates to our original volume. However, we need to convert it to kelvin. We do this simply by adding 273 degrees to the 30 degrees, since 273 is the constant for kelvin.

We do not know our second volume, however we know out T2. It is -8 degrees, and don't forget to convert it to Kelvin.

So, when we plug all of these numbers into the equation, we are left with V2 to find. To do this we cross multiply (V1 x T2) and then divide by T1. That leaves us with the number for V2. Don't forget to round to the least # of sig figs! And you can divide V1 by T1, and then divide V2 by T2, to ensure your answers are the same, since they are directly porportional and need to be equal to each other.

Hope I could help!

8 0

4 years ago

Does mint actually cool things down

PtichkaEL [24]

The cooling of a mint is just a sensation if you were to put mints into warm water the water would remain warm because it is just a cooling sensation. I hope this helps:)

3 0

4 years ago