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4 years ago

Explain why you usually can't use just a single spectrum line to confirm the identity of an element

1 answer:

8 0

You can't usually just use a single spectrum line to confirm the identity of an element because there are cases that the emission line id not clearly defined. When the emission line is very weak compared to surrounding noise, in which case the more datapoints you have to build up confidence for the existence of a particular emission spectra, the better.

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What is the pH of a 0.083 solution of HCI

quester [9]

Answer:

The pH is 1.08, being an acid pH

Explanation:

pH is a parameter used to measure the degree of acidity or alkalinity of a substance. The pH scale ranges from 0 to 14. Values less than 7 indicate the acidity range and those greater than 7 indicate alkalinity or basicity. Value 7 is considered neutral. Mathematically, pH is the negative logarithm of the molar concentration of hydrogen or proton ions (H⁺) or hydronium ions (H₃O⁺).

pH= - log [H⁺]= - log [H₃O⁺]

A strong acid is an acid that completely dissociates into hydrogen ions and anions in solution. This implies that the initial concentration of acid is equal to the final concentration of H₃O⁺. This occurs with acid HCl.

So, pH is calculated as:

pH= - log (0.083)

pH= 1.08

<u><em>The pH is 1.08, being an acid pH</em></u>

8 0

3 years ago

How many moles of ammonia can be formed from 4.0 mol H2

Bess [88]

Answer: 1. 2.7 moles of ammonia are formed

2. 12.0 moles of hydrogen are required

3. 2.0 moles of nitrogen are required

Explanation:

The balanced chemical equation is:

$N_2+3H_2\rightarrow 2NH_3$

According to stoichiometry:

3 moles of hydrogen form = 2 moles of ammonia

Thus 4.0 moles of hydrogen form = $\frac{2}{3}\times 4.0=2.7moles$ of ammonia

According to stoichiometry:

2 moles of ammonia are formed by = 3 moles of hydrogen

Thus 8.0 moles of ammonia are formed by = $\frac{3}{2}\times 8.0=12.0moles$ of hydrogen

According to stoichiometry:

3 moles of hydrogen react with = 1 mole of nitrogen

Thus 6.0 moles of hydrogen react with = $\frac{1}{3}\times 6.0=2.0moles$ of nitrogen

3 0

3 years ago

Carbon fixation occurs during the light reactions.

Ksju [112]

Answer:

True

Explanation:

5 0

2 years ago

Read 2 more answers

50.0 g of Potassium chloride reacts with 50.0 g of oxygen to produce KCIO3. After writing

IgorLugansk [536]

Explanation:

If 50.0 grams of Zinc are reacted with 50.0 grams of Hydrogen Chloride ... 50.09 Zn x 1 mol Zn , Imol ZnCl2 , 136.4g. ... If a decomposition reaction produces a 75.0% yield for the oxygen by mass (128.0 grams were.

5 0

3 years ago

onsider the reversible dissolution of lead(II) chloride. P b C l 2 ( s ) − ⇀ ↽ − P b 2 + ( a q ) + 2 C l − ( a q ) PbClX2(s)↽−−⇀

Sveta_85 [38]

Answer:

9.34x10^-4

Explanation:

Step 1:

The balanced equation for the reaction.

PbCl2( s ) <=> Pb^2+(aq) + 2Cl^−(aq)

Step 2:

Data obtained from the question:

Mass of PbCl2 = 0.2393 g

Volume = 50mL

concentration of Pb^2+, [Pb^2+] = 0.0159 M

Concentration of Cl^-, [Cl^-] = 0.0318 M

Equilibrium constant, Kc =?

Step 3:

Determination of the number of mole PbCl2.

The number of mole of PbCl2 can be obtained as follow:

Molar Mass of PbCl2 = 207 + (35.5x2) = 278g/mol

Mass of PbCl2 = 0.2393 g

Number of mole =Mass /Molar Mass

Number of mole of PbCl2 = 0.2393/278 = 8.61x10^-4 mole

Step 4:

Determination of Molarity of PbCl2.

At this stage we shall obtain the molarity of PbCl2. This is shown below:

Mole of PbCl2 = 8.61x10^-4 mole

Volume = 50mL = 50/1000 = 0.05L

Molarity of PbCl2 =?

Molarity = mole /Volume

Molarity of PbCl2 = 8.61x10^-4/0.05

Molarity of PbCl2 = 0.01722 M

Step 5:

Determination of the equilibrium constant Kc.

PbCl2( s ) <=> Pb^2+(aq) + 2Cl^−(aq)

The equilibrium constant Kc for the equation above is given by:

Kc = [Pb^2+] [Cl^-]^2 / [PbCl2]

[Pb^2+] = 0.0159 M

[Cl^-] = 0.0318 M

[PbCl2] = 0.01722 M

Kc =?

Kc = [Pb^2+] [Cl^-]^2 / [PbCl2]

Kc = 0.0159 x (0.0318)^2/ 0.01722

Kc = 9.34x10^-4

5 0

3 years ago