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3 years ago

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Element X forms an oxide with chemical formula X20. Experimental tests show that X20 contains 25.8 % oxygen, and x contains 74.2

% by mass.
(b) Use this information to identify element X.

1 answer:

lawyer [7]3 years ago

6 0

Hdhdhdh hdhdhdh hdhdhdh

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A gas of 19 mL at a pressure of 740 mmHg can be expected to change its pressure when its volume changes to 30. mL. Express its n

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To solve this we assume that the gas is an ideal gas. Then, we can use the ideal gas equation which is expressed as PV = nRT. At a constant temperature and number of moles of the gas the product of PV is equal to some constant. At another set of condition of temperature, the constant is still the same. Calculations are as follows:

P1V1 =P2V2

P2 = P1V1/V2

P2 = 740mmhg x 19 mL / 30 mL

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How many milliliters of 0.1 m hcl is required to react with 0.15g sodium carbonate (na2co3?

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1) Write the balanced chemical equation

2HCl + Na2 CO3 ----------> 2NaCl + H2CO3

2) Write the molar ratios:

2 mol HCl : 1 mol Na2CO3 : 2 mol NaCl : 1 mol H2CO3

3) Convert 0.15g of sodium carbonate to number of moles

3a) Calculate the molar mass of Na2CO3

Na: 2 * 23 g/mol = 46 g/mol

C: 12 g/mol =

O: 3 * 16 g/mol = 48 g/mol

molar mass = 46g/mol + 12g/mol + 48g/mol = 106 g/mol

3b.- Calculate the number of moles of Na2CO3

# moles = grams / molar mass = 0.15 g / 106 g/mol = 0.0014 mol Na2CO3

4) Calculate the number of moles of HCl from the molar proportion:

[0.0014 mol Na2CO3] * [2 mol HCl / 1 mol Na2CO3] = 0.0028 mol HCl

5) Calculate the volume of HCl from the definition of Molarity

Molarity, M = # moles / volume in liters

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0.028 liters * 1000 ml / liter = 28 ml.

Answer: 28 mililiters of 0.1 M HCl.

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3 years ago

Given that 25.0 mL of mercury has a mass of 340.0 g, calculate (a) the density of mercury and (b) the mass of 120.0 mL of mercur

natita [175]

Answer :

(a) The density of mercury is, 13.6 g/ml

(b) The mass of 120.0 ml of mercury is, 1632 grams

Explanation :

(a) Now we have to calculate the density of mercury.

<u>Given :</u>

Volume of mercury = 25.0 ml

Mass of mercury = 340.0 g

Formula used :

$\text{Density of mercury}=\frac{\text{Mass of mercury}}{\text{Volume of mercury}}$

$\text{Density of mercury}=\frac{340.0g}{25.0ml}=13.6g/ml$

Therefore, the density of mercury is, 13.6 g/ml

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As, 25.0 ml of mercury has mass = 340.0 g

So, 120.0 ml of mercury has mass = $\frac{120.0ml}{25.0ml}\times 340.0g=1632g$

Therefore, the mass of 120.0 ml of mercury is, 1632 grams

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3 years ago

A piece of asphalt has a volume of 5.0 cm3 and a mass of 7.5 g. What is the density of the asphalt?

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Density = mass / volume
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Please get back to me if I’m right or wrong :)

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3 years ago