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kogti [31]
3 years ago
12

Why is Ce3+ colorless and Ce4+ colored

Chemistry
1 answer:
umka21 [38]3 years ago
3 0

Answer:

Both Ce3+ and Yb3+ are colorless. This is because, they have only 1 unpaired electron in 4f orbitals and that transition is in UV region.

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A strontium hydroxide solution is prepared by dissolving 10.60 gg of Sr(OH)2Sr(OH)2 in water to make 47.00 mLmL of solution.What
NeTakaya

Answer:

Approximately 1.854\; \rm mol\cdot L^{-1}.

Explanation:

Note that both figures in the question come with four significant figures. Therefore, the answer should also be rounded to four significant figures. Intermediate results should have more significant figures than that.

<h3>Formula mass of strontium hydroxide</h3>

Look up the relative atomic mass of \rm Sr, \rm O, and \rm H on a modern periodic table. Keep at least four significant figures in each of these atomic mass data.

  • \rm Sr: 87.62.
  • \rm O: 15.999.
  • \rm H: 1.008.

Calculate the formula mass of \rm Sr(OH)_2:

M\left(\rm Sr(OH)_2\right) = 87.62 + 2\times (15.999 + 1.008) = 121.634\; \rm g \cdot mol^{-1}.

<h3>Number of moles of strontium hydroxide in the solution</h3>

M\left(\rm Sr(OH)_2\right) =121.634\; \rm g \cdot mol^{-1} means that each mole of \rm Sr(OH)_2 formula units have a mass of 121.634\; \rm g.

The question states that there are 10.60\; \rm g of \rm Sr(OH)_2 in this solution.

How many moles of \rm Sr(OH)_2 formula units would that be?

\begin{aligned}n\left(\rm Sr(OH)_2\right) &= \frac{m\left(\rm Sr(OH)_2\right)}{M\left(\rm Sr(OH)_2\right)}\\ &= \frac{10.60\; \rm g}{121.634\; \rm g \cdot mol^{-1}} \approx 8.71467\times 10^{-2}\; \rm mol\end{aligned}.

<h3>Molarity of this strontium hydroxide solution</h3>

There are 8.71467\times 10^{-2}\; \rm mol of \rm Sr(OH)_2 formula units in this 47\; \rm mL solution. Convert the unit of volume to liter:

V = 47\; \rm mL = 0.047\; \rm L.

The molarity of a solution measures its molar concentration. For this solution:

\begin{aligned}c\left(\rm Sr(OH)_2\right) &= \frac{n\left(\rm Sr(OH)_2\right)}{V}\\ &= \frac{8.71467\times 10^{-2}\; \rm mol}{0.047\; \rm L} \approx 1.854\; \rm mol \cdot L^{-1}\end{aligned}.

(Rounded to four significant figures.)

5 0
3 years ago
Antacids work to relieve stomach acids because of which of the following types of reactions?
Anastaziya [24]

<u>Answer:</u> The correct answer is Option B.

<u>Explanation:</u>

Decomposition is a type of chemical reaction in which larger compound breaks down into two or more smaller compounds.

AB\rightarrow A+B

Double displacement reactions is defined as the chemical reaction in which exchange of ions takes place.

AB+CD\rightarrow AD+CB

Synthesis reaction is a type of reaction in which two or more smaller compounds combines to form a single large compound.

A+B\rightarrow AB

Single displacement reaction is a type of reaction in which a more reactive metal displaces a less reactive metal from its chemical reaction.

A+BC\rightarrow AC+B

In stomach, an acid is present known as hydrochloric acid and to neutralize its effect, antacid is taken which has CaCO_ as a component.

The reaction between HCl and CaCO_3 is a type of neutralization reaction and it is a type of double displacement reaction.

The equation between the two follows:

CaCO_3+HCl\rightarrow CaCl_2+H_2O+CO_2

Hence, the correct answer is Option B.

4 0
3 years ago
The most simple level of organization in living things is the tissue level.
murzikaleks [220]
<span>The simplest level of organization for living things is a single organelle, which is composed of aggregates of macromolecules. so it is false</span>
3 0
3 years ago
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I need help with this question please <br> Chemistry
ivolga24 [154]
I cannot see it can you make it bigger by any chance dm me on Instagram
5 0
3 years ago
*blank* carry blood away from the heart, while *blank* carry blood back to the heart.
worty [1.4K]

Answer:

i think its C im not so sure

Explanation:

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5 0
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