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Anit [1.1K]
3 years ago
12

A newly discovered element, Z, has two naturally occurring isotopes. 90.3 percent of the sample is an isotope with a mass of 267

.8 u, and 9.7 percent of the sample is an isotope with a mass of 270.9 u. What is the weighted average atomic mass for this element?
Chemistry
1 answer:
kirill115 [55]3 years ago
4 0
Ok so, remember that t<span>he average atomic mass is what is seen on the periodic table. It is the average mass of all of the isotopes with their frequency taken into account. What you need to do is add the products of the masses and frequencies Just like this:</span>

<span>0.903*267.8 + 0.097*270.9
When you add it the result is what you are looking for</span>
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At room temperature (20°C} and pressure, the density of air is 1.189 g/L. An object will float in air if its density is less tha
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Explanation:

Density =\frac{Mass}[Volume}

Density of the air ,d= 1.189 g/L

(a) Density of the evacuated ball

Mass of the ball ,m = 0.12 g

Volume of the ball =V=560 cm^3=560 ml=0.560 L

D =\frac{0.12 g}{0.560 L}=0.214 g/L

D<d, teh evacuated ball will flaot in air.

(b) Density of the evacuated ball D = 0.214 g/L

Density of carbon dioxide gas = d_1=1.830 g/L

Mass of the carbon dioxide gas :

1.830 g/L\times 0.560 L=1.0248 g

Total density of filled ball with carbon dioxide gas:

\frac{0.12 g+1.0248 g}{0.560 L}==2.044 g/L

The ball filled with carbon dioxide will not float in the air because total density of filled ball is greater than the density of an air.

(c) Density of the evacuated ball D = 0.214 g/L

Density of hydrogen gas = d_2=0.0899 g/L

Mass of the hydrogen gas :

1.830 g/L\times 0.560 L=0.050344 g

Total density of filled ball with hydrogen gas:

\frac{0.12 g+0.050344 g}{0.560 L}==0.3041 g/L

The ball filled with hydrogen will float in the air because total density of filled ball is lessor than the density of an air.

(d) Density of the evacuated ball D = 0.214 g/L

Density of oxygen gas = d_3=1.330 g/L

Mass of the oxygen gas :

1.330 g/L\times 0.560 L=1.7448 g

Total density of filled ball with oxygen gas:

\frac{0.12 g+1.7448 g}{0.560 L}=1.5442 g/L

The ball filled with oxygen will not float in the air because total density of filled ball is greater than the density of an air.

(e) Density of the evacuated ball D = 0.214 g/L

Density of nitrogen gas = d_4=1.165 g/L

Mass of the nitrogen gas :

1.165 g/L\times 0.560 L=0.6524 g

Total density of filled ball with nitrogen gas:

\frac{0.12 g+0.6524 g}{0.560 L}==1.3792 g/L

The ball filled with nitrogen will not float in the air because total density of filled ball is greater than the density of an air.

f) Mass must be added to sink the ball = m

Density of ball > Density of the air ; to sink the ball.

\frac{0.12g +m}{0.560L}>1.189 g/L

m > 0.54584 g

For any case weight added to ball to make it sink in an air should be grater than the value of 0.54584 grams.

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The half-life of the reaction is 50 minutes

Data;

  • Time = 43 minutes
  • Type of reaction = first order
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<h3>Reaction Constant</h3>

Let the initial concentration of the reaction be X_0

The reactant left = (1 - 0.45) X_0 = 0.55 X_0 = X

For a first order reaction

\ln(\frac{x}{x_o}) = -kt\\ k = \frac{1}{t}\ln (\frac{x_o}{x}) \\ k = \frac{1}{43}\ln (\frac{x_o}{0.55_o})\\ k = 0.013903 min^-^1

<h3>Half Life </h3>

The half-life of a reaction is said to be the time required for the initial amount of the reactant to reach half it's original size.

x = \frac{x_o}{2} \\t = t_\frac{1}{2} \\t_\frac{1}{2} = \frac{1}{k}\ln(\frac{x_o}{x_o/2})\\

Substitute the values

t_\frac{1}{2} = \frac{1}{k}\ln(2)=\frac{0.6931}{0.013903}\\t_\frac{1}{2}= 49.85 min = 50 min

The half-life of the reaction is 50 minutes

Learn more on half-life of a first order reaction here;

brainly.com/question/14936355

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Which term refers to the speed at which reactants are converted into products?
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