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bixtya [17]
3 years ago
5

A chemist prepares a solution of calcium bromide CaBr2 by measuring out 4.81μmol of calcium bromide into a 50.mL volumetric flas

k and filling the flask to the mark with water. Calculate the concentration in /μmolL of the chemist's calcium bromide solution. Round your answer to 2 significant digits.
Chemistry
1 answer:
Mariana [72]3 years ago
4 0

Answer:

The concentration of the CaBr2 solution is 96 µmol/L

Explanation:

<u>Step 1:</u> Data given

Moles of Calciumbromide (CaBr2) = 4.81 µmol

Volume of the flask = 50.0 mL = 0.05 L

<u>Step 2:</u> Calculate the concentration of Calciumbromide

Concentration CaBr2 = moles CaBr2 / volume

Concentration CaBr2 = 4.81 µmol / 0.05 L

Concentration CaBr2 = 96.2 µmol /L = 96.2 µM

The concentration of the CaBr2 solution is 96 µmol/L

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which atom has a change in oxidation number of -3 in the following redox reaction K2Cr2O7 + H2O +S --&gt; KOH + Cr2O3 +SO2
yaroslaw [1]
You have to calculate the oxidation estates of the atoms in each compound.

I will start with K2Cr2O7 because I believe that Cr is the best candidate to reduce its oxidation number in 3 units.

In K2Cr2O7:

- K has oxidation state of 1+, then K2 has a charge of 2* (1+) = 2+.

- O has oxidation state of 2*, then O7 has a charge of 7* (2-) = 14-.

That makes that Cr2 has charge of 14 - 2 = +12, so each Cr has +12/2 = +6 oxidation state.

In Cr2O3:

- O has oxidation state of 2-, then O3 has charge 3 * (2-) = - 6

- Then, Cr2 has charge 6+, and each Cr has charge 6+ / 2 = 3+.

So, we have seen that Cr reduced its oxidation state in 3 units, from 6+ to 3+.

Answer: Cr has a change in oxidation number of - 3.
6 0
3 years ago
Where would the electrons in the 3d sublevel be found? Possibly in any shell only in the n = 3 energy level in energy levels &gt
postnew [5]

Answer:

In the n = 3 energy level

Explanation:

There's is no further explanation for this.

All the electrons in an energy level are distribuited according to the period in the periodic table they are.

So, if we have an atom in period 1, like Hydrogen (H), that atom would only have 1 level energy (n = 1) and in that level, we only have the sub level 1s.

Electrons in the 3d sublevel, are found mostly in all the transition metals of period 3, and it can go from 1 to 10 electrons. To be with the 3d sub level it's neccesary that the energy level to be 3.

energy levels beyond that, like n = 4, we have electrons occupying the 3d sub level, so, primordly, the 3d is found only in energy level 3.

Hope this helps

4 0
2 years ago
A gas is at 35.0°c and 3.50 l. what is the temperature at 7.00 l?
Degger [83]

Answer:

363C

Explanation:

V = KT  and T = V/K

3.5=k(35+273) = 308k

k=3.5/308 =0.011

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2 years ago
Which statement below best describes the Theory of Plate Tectonics?
k0ka [10]

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3 0
3 years ago
Read 2 more answers
What is the molarity of a solution that contains 15.0g of naoh per 500.0 ml of solution ​
VARVARA [1.3K]

Answer:

0.4 M

Explanation:

Molarity is defined as moles of solute, which in your case is sodium hydroxide,  

NaOH

, divided by liters of solution.

molarity

=

moles of solute

liters of solution

Notice that the problem provides you with the volume of the solution, but that the volume is expressed in milliliters,  

mL

.

Moreover, you don't have the number of moles of sodium hydroxide, you just have the mass in grams. So, your strategy here will be to

determine how many moles of sodium hydroxide you have in that many grams

convert the volume of the solution from milliliters to liters

So, to get the number of moles of solute, use sodium hydroxide's molar mass, which tells you what the mass of one mole of sodium hydroxide is.

7

g

⋅

1 mole NaOH

40.0

g

=

0.175 moles NaOH

The volume of the solution in liters will be

500

mL

⋅

1 L

1000

mL

=

0.5 L

Therefore, the molarity of the solution will be

c

=

n

V

c

=

0.175 moles

0.5 L

=

0.35 M

Rounded to one sig fig, the answer will be

c

=

0.4 M

8 0
2 years ago
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