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3 years ago

Builders and dentists must store plaster of Paris,

Chemistry

1 answer:

eimsori [14]3 years ago

3 0

Answer:

547 L of water vapour

Explanation:

Equation of reaction: 2[CaSO4.2H20] + Heat ---> 2[CaSO4.½H2O] + 3H20

From the equation of reaction above, 2 moles of gypsum when heated produces 2 moles of plaster of Paris and 3 moles of water vapour.

Molar mass of gypsum = 172 g/mol

Molar mass of H2O = 18 g/mol

Therefore, 2 * 172 g of gypsum produces 3 * 18 g of water vapour

i.e. 344 g of gypsum produces 54 g of H2O

2 Kg(2000 g) of gypsum will produce (54 * 2000)/344 g of water vapour = 313.95 of water vapour.

Volume of water vapour produced = mass/density

Volume of water vapour = 313.95 g/ 0.574 g/L = 547 L of water vapour

Therefore 547 L of water vapour are produced

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Answer: Option (b) is the correct answer.

Explanation:

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Generally, a covalent bond is formed between non-metals.

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As nitrogen has 5 valence electrons and an oxygen atom has 6 valence electrons. So, there occurs unequal sharing of electrons between the two.

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White light is what the eye sees when wavelengths of all colours reach the eye.

It is a combination of Red, Blue and Green wavelengths of light, that is perceived as white.

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4 years ago

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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

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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.

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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

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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.

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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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What is the mass (g) of 0.25mols of NaCl?

What you need for these equations are a calculator, periodic table and the following equation:

Mass (g) = Mr x Moles (important equation to remember)

In this case we already know the moles as it's in the question, 0.25 moles.

to find the Mr, you need to look at your periodic table. Find the relative atomic mass of Na and Cl and add the two numbers together.

Na = 22.99

Cl = 35.45

NaCl = 58.4

Now just put all of the numbers into the equation.

0.25 x 58.4 = 14.6g

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