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OverLord2011 [107]
3 years ago
7

Could you please Calculate the number of atom of 40K (potassium 40) in 1gram of KCl. Taking into account the isotopic abundance

of 40K that is 0.0118%)
Chemistry
1 answer:
Crank3 years ago
8 0

Answer:

9.53*10^{17} atoms of 40K

Explanation:

You can use the molecular mass and the Avogadro´s number, in the following formula:

N_{40K=\frac{m_{KCl}}{M_{MKCl}}}*N_{Avogadro}*(IA_{40k})

where m_{KCl} is the sample mass, M_{KCl} is the molecular mass of the KCl and IA(40K) is the isotopic abundance of 40K.

Now replacing the values, you can find:

N_{40K}=\frac{1g}{74.5513\frac{g}{mol}}*6.022*10^{23}mol^{-1} *0.000118

N_{40K}=9.53*10^{17} atoms

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OLga [1]
The smallest volume is 30 cm^3.
8 0
3 years ago
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Given these reactions, where X represents a generic metal or metalloid 1 ) H 2 ( g ) + 1 2 O 2 ( g ) ⟶ H 2 O ( g ) Δ H 1 = − 241
Mazyrski [523]

Answer:

-767,2kJ

Explanation:

It is possible to sum enthalpies of half-reactions to obtain the enthalpy of a global reaction using Hess's law. For the reactions:

1) H₂(g) + ¹/₂O₂(g) ⟶ H₂O(g) ΔH₁= −241.8 kJ

2) X(s) + 2Cl₂(g) ⟶ XCl₄(s) ΔH₂= +361.7 kJ

3) ¹/₂H₂(g) + ¹/₂Cl₂(g) ⟶ HCl (g) ΔH₃= −92.3 kJ

4) X(s) + O₂(g) ⟶ XO₂(s) ΔH₄= − 607.9 kJ

5) H₂O(g) ⟶ H₂O(l) ΔH₅= − 44.0 kJ

The sum of (4) - (2) produce:

6) XCl₄(s) + O₂(g) ⟶ XO₂(s) + 2Cl₂(g) ΔH₆ = ΔH₄ - ΔH₂ = -969,6 kJ

(6) + 4×(3):

7) XCl₄(s) + 2H₂(g) + O₂(g) ⟶ XO₂(s) + 4HCl(g) ΔH₇ = ΔH₆ + 4ΔH₃= -1338,8 kJ

(7) - 2×(1):

8) XCl₄(s) + 2H₂O(g) ⟶ XO₂(s) + 4HCl(g) ΔH₈ = ΔH₇ - 2ΔH₁= -855,2kJ

(8) - 2×(5):

9) XCl₄(s) + 2H₂O(l) ⟶ XO₂(s) + 4HCl(g) ΔH₉ = ΔH₈ - 2ΔH₅= <em>-767,2kJ</em>

I hope it helps!

6 0
3 years ago
Which statement is correct about the rate of chemical reactions?
ratelena [41]

Answer:

It increases when a catalyst is added.

Explanation:

The following factors control reaction rates:

1. Nature of reactants

2. Concentration of the reactants or pressure of gaseous

3. Temperature

4. Presence of catalyst

5. Sunlight

The addition of a foreign body to a reaction may influence the speed of the reaction. If a foreign body increases the rate of reaction, it is a called a positive catalyst or simply a catalyst. A negative catalyst is called an inhibitor.

A catalyst is a substance that is introduced into a chemical reaction to change the rate of the reaction without itself being affected at the end of the reaction.

Catalysts helps to reduce reaction time of many slow reactions. Most catalysts are specific in their actions and works on certain reactions or substrates.

Temperature change has a considerable effect on reaction rates since temperature is directly proportional to the average kinetic energy of reacting particles. Generally, reaction rate varies as temperature directly.

8 0
3 years ago
Harvey kept a balloon with a volume of 348 milliliters at 25.0˚C inside a freezer for a night. When he took it out, its new volu
ad-work [718]

Initial volume of the balloon = V_{1}= 348 mL

Initial temperature of the balloon T_{1} = 25.0^{0}C + 273 = 298 K

Final volume of the balloon V_{2} = 322 mL

Final temperature of the balloon = T_{2} = ?

According to Charles law, volume of an ideal gas is directly proportional to the temperature at constant pressure.

\frac{V_{1} }{T_{1} } =\frac{V_{2} }{T_{2} }

On plugging in the values,

\frac{348mL}{298 K} =\frac{322 mL}{T_{2} }

T_{2} =276 K

Therefore, the temperature of the freezer is 276 K

5 0
3 years ago
Solve for y in the following problem: 5.3 x 10- (y)(2y)
weqwewe [10]

Answer:

The value of y = 5.1478

Explanation:

The linear equation is an equation obtained when a linear polynomial is equated to zero. When the solution obtained on solving the equation is substituted in the equation in place of the unknown, the equation gets satisfied.

The given equation: 5.3 x 10- (y)(2y) = 0

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⇒ 2y² = 53

⇒ y² = 53 ÷ 2 = 26.5

⇒ y = √26.5 = 5.1478

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