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dusya [7]
3 years ago
9

The student plans to conduct a spectrophotometric analysis to determine the concentration of Cu2+(aq) in a solution. The solutio

n has a small amount of Co(NO3)2 (aq) present as a contaminant. The student is given a diagram below, which shows the absorbance curves for aqueous solutions of Co2+ (aq) and Cu2+ (aq)
c. The spectrophotometer available to the student has a wavelength range of 400 nm to 700 nm. What wavelength should the student use to minimize the interference from the presence of the Co2+ (aq)?

Chemistry
1 answer:
Lelechka [254]3 years ago
6 0

Answer:

The wavelength the student should use is 700 nm.

Explanation:

Attached below you can find the diagram I found for this question elsewhere.

Because the idea is to minimize the interference of the Co⁺²(aq) species, we should <u>choose a wavelength in which its absorbance is minimum</u>.

At 400 nm Co⁺²(aq) shows no absorbance, however neither does Cu⁺²(aq). While at 700 nm Co⁺²(aq) shows no absorbance and Cu⁺²(aq) does.

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A gas occupies 100 mL at 150. kPa. Find its volume at 200. kPa. You must show all your work to receive credit. Be sure to identi
PtichkaEL [24]

The Boyle-Mariotte's law or Boyle's law is one of the laws of gases that <u>relates the volume (V) and pressure (P) of a certain amount of gas maintained at constant temperature</u>, as follows:

PV = k

where k is a constant.

We can relate the state of a gas at a specific pressure and volume to another state in which the same gas is at different P and V since the product of both variables is equal to a constant, according to the Boyle's law, which will be the same regardless of the state of the gas. In this way,

P₁V₁ = P₂V₂

Where P₁ and V₁ is the pressure and volume of the gas to a state 1 and P₂ and V₂ is the pressure and volume of the same gas in a state 2.

In this case, in the state 1 the gas occupies a volume V₁ = 100 mL at a pressure of P₁ = 150 kPa. Then, in the state 2 the gas occupies a volume V₂ (that we must calculate through the boyle's law) at a pressure of P₂ = 200 kPa.  Substituting these values in the previous equation and clearing V₂, we have,

P₁V₁ = P₂V₂ → V₂ = \frac{P1V1}{P2}  

→ V₂ = \frac{100 mL x 150 kPa}{200 kPa}

→ V₂ = 75 mL

Then, the volume occupied by the gas at 200 kPa is V₂ = 75 mL

6 0
3 years ago
Various members of a class of compounds, alkenes, react with hydrogen to produce a corresponding alkane. Termed hydrogenation, t
Vitek1552 [10]

<u>Answer:</u> The mass of decane produced is 1.743\times 10^2g

<u>Explanation:</u>

To calculate the number of moles, we use the equation:  

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}       ......(1)

Mass of hydrogen gas = 2.45 g

Molar mass of hydrogen gas = 2 g/mol

Putting values in equation 1:, we get:

\text{Moles of }H_2=\frac{2.45g}{2g/mol}=1.225mol

The chemical equation for the hydrogenation of decene follows:

C_{10}H_{20}(l)+H_2(g)\rightarrow C_{10}H_{22}(s)

As, decene is present in excess. So, it is considered as an excess reagent.

Thus, hydrogen gas is a limiting reagent because it limits the formation of products.

By Stoichiometry of the reaction:

1 mole of hydrogen gas produces 1 mole of decane.

So, 1.225 moles of hydrogen gas will produce = \frac{1}{1}\times 1.225=1.225mol of decane

Now, calculating the mass of decane by using equation 1, we get:

Moles of decane = 1.225 mol

Molar mass of decane = 142.30 g/mol

Putting values in equation 1, we get:

1.225mol=\frac{\text{Mass of decane}}{142.30g/mol}\\\\\text{Mass of carbon dioxide}=(1.225mol\times 142.30g/mol)=174.3g=1.743\times 10^2g

Hence, the mass of decane produced is 1.743\times 10^2g

5 0
3 years ago
I need to know what occupied vs full means for chemistry
Anastaziya [24]
You can get the answer on quizlet or google
7 0
3 years ago
Elements that have complete valence electron shells are mostly found in the
nika2105 [10]
Noble gases have complete valence electron shells
6 0
3 years ago
Read 2 more answers
The thermite reaction reacts iron (III) oxide, Fe2O3, with aluminium powder,Al, the form aluminium oxide, Al2O3 and iron, Fe.
lara [203]

Answer:

<u><em>This answer assumes that the strated "16.0g of iron" was meant to be 16.0 grams of iron(III) oxide.</em></u>

Explanation:

To start, the thermite equation must be balanced.

I find:

1Fe2O3 + 2Al = 1Al2O3 + 2Fe

This tells us we need 2 moles of Al for every 1 mole of Fe2O3.  

Now calculate the moles of each reactant:

Moles Fe2O3:  16.0 g/159.7 g/mole = <u>0.100 moles Fe2O3</u>

Moles Al:  8.1 /26.98 g/mole = <u>0.300 moles Al</u>

The balanced equation says that in order to react all of the Fe2O3 we'd need twice that amount (in moles) of the Al.  (0.100 moles Fe2O3)*(2) = 0.200 moles Al.

<u>Which of the two reactants is the limiting reagent?</u>

We have more than enough moles of Al to react with 0.10 moles of Fe2O3.  (We have 0.300 moles Al and all we need is 0.200 moles to react with the 0.10 moles of Fe2O3.  <em>Fe2O3 is the limiting reagent.</em>

<u><em>Calculate the maximum mass of iron of iron that could be formed using these quantities of reactants.</em></u>

The balanced equation tells us that we will obtain 2 moles of Fe for every 1 mole of Fe2O3 consumed.  Since Fe2O3 is the limiting reagent, we will assume that it completely reacts.  That means 0.1 moles of Fe2O3 is reacted.  Since we expect twice that many moles of Fe, we should obtain 0.200 moles of Fe.  At 55.85 g/mole, we should obtain:

(0.200 moles Fe)*(55.85 g Fe/mole Fe) = 11.2 grams Fe

<em></em>

<em></em>

5 0
2 years ago
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