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3 years ago

Unit: Stoichiometry

Chemistry

1 answer:

Reika [66]3 years ago

7 0

Answer:

1. 2.41 × 1023 formula units

2. 122 L

3. 7.81 L

Explanation:

1. Equation of the reaction: 2 Na(NO3) + Ca(CO3) ---> Na2(CO3) + Ca(NO3)2

Mole ratio of NaNO3 to CaCO3 = 2 : 1

Moles of CaCO3 = mass/molar mass

Mass of CaCO3 = 20 g; molar mass of CaCO3 = 100 g

Moles of CaCO3 = 20 g/100 g/mol = 0.2 moles

Moles of NaNO3 = 2 × 0.2 moles = 0.4 moles

1 Mole of NaNO3 = 6.02 × 10²³ formula units

0.4 moles of NaNO3 = 0.4 × 6.02 × 10²³ = 2.41 × 1023 formula units

2. Equation of reaction : 2 H2O ----> 2 H2 + O2

Mole ratio of oxygen to water = 1 : 2

At STP contains 6.02 × 10²³ molecules = 1 mole of water

6.58 × 10²⁴ molecules = 6.58 × 10²⁴ molecules × 1 mole of water/ 6.02 × 10²³ molecules = 10.93 moles of water

Moles of oxygen gas produced = 10.93÷2 = 5.465 moles of oxygen gas

At STP, 1 mole of oxygen gas = 22.4 L

5.465 moles of oxygen gas = 5.465 moles × 22.4 L/1 mole = 122 L

3.Equation of reaction: 6 K + N2 ----> 2 K3N

Mole ratio of Nitrogen gas and potassium = 6 : 1

Moles potassium = mass/ molar mass

Mass of potassium = 90.0 g, molar mass of potassium = 39.0 g/mol

Moles of potassium = 90.0 g / 39.0 g/mol = 2.3077moles

Moles of Nitrogen gas = 2.3077 moles / 6 = 0.3846 moles

At STP, 1 mole of nitrogen gas = 22.4 L

0.3486 moles of oxygen gas = 0.3486 moles × 22.4 L/1 mole = 7.81 L

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Answer:

By filtration

Explanation:

In the container, pour water and shake the mixture very well.

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3 years ago

What would be the mass of 3 moles of water molecules?

ankoles [38]

Answer:

$\boxed {\boxed {\sf A. \ 54 \ grams }}$

Explanation:

To convert from moles to grams, we must use the molar mass.

Recall that water's molecular formula is H₂O. It contains hydrogen and oxygen. Look up the two elements masses on the Periodic Table.

Hydrogen (H): 1.008 g/mol
Oxygen (O): 15.999 g/mol

Now, use these masses to find water's mass. The subscript of 2 tells us there are 2 atoms of hydrogen, so we multiply hydrogen's mass by 2 and add oxygen's.

H₂O= 2(1.008 g/mol) + 15.999 g/mol = 18.015 g/mol

Use the molar mass as a ratio.

$\frac{18.015 \ g \ H_2 O}{ 1 \ mol \ H_2 O}$

Multiply by the given number of moles.

$3 \ mol \ H_2O*\frac{18.015 \ g \ H_2 O}{ 1 \ mol \ H_2 O}$

The moles of water will cancel.

$3 *\frac{18.015 \ g \ H_2 O}{ 1 }$

$3 *{18.015 \ g \ H_2 O}$

$54.045 \ g \ H_2O$

Round to the nearest whole number. The 0 in the tenth place tells us to leave the number as is.

$54 \ g \ H_2O$

There are about 54 grams of water in 3 moles.

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3 years ago

Read 2 more answers

if a gas sample has a pressure of 761 mmhg at 0.00°c by how much does the temperature have to decrease to lower the pressure to

Nady [450]

<h3>Answer:</h3>

272.43 K or -0.718°C

<h3>Explanation:</h3>

We are given;

The initial pressure,P1 as 761 mmHg

Initial temperature, T1 as 0.00°C which is equivalent to 273.15 K

Final pressure as 759 mmHg

We are required to calculate the final temperature;

According to pressure law, the pressure of a gas and absolute temperature are directly proportional at constant volume.

That is; Pα T

Therefore, at varying pressure and temperature,

$\frac{P1}{T1}=\frac{P2}{T2}$

To get final temperature;

$T2=\frac{P2T1}{P1}$

$T2=\frac{(759 mmHg)(273.15K)}{761 mmHg}$

$T2=272.43K$

Therefore, the final temperature will be 272.43 K or -0.718°C

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3 years ago

I'm looking at the barometer in my lab as I type this question. It says the pressure is 968 torr. What is this pressure expresse

Ksenya-84 [330]

Answer:

1.27 atm.

Explanation:

The following data were obtained from the question:

Pressure (P) in torr = 968 torr

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Thus, we can convert from torr to atm by doing the following:

Recall:

760 torr = 1 atm

Therefore,

968 torr = 968/760 = 1.27 atm

Therefore, 968 torr is equivalent to 1.27 atm.

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What is the wavelength range,in nanometer,for infrared light? In what portion of this range does the earth receive IR from the s

andrezito [222]

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Explanation:

The wavelength range of Infrared radiation is 700 nanometers to 1 millimeter. This also translates to a frequency range of 430 TeraHertz to 300 Giga Hertz.

Because the sun is a star and is hot in comparison to earth and other planetary bodies, the bigger range of infrared radiation it emits is in the near-infrared which is mainly composed of wavelength below 4 micrometers.

The earth's surface produces infrared radiation of the mid-infrared range while cooler substances will produce far-infrared range

The thermal range of infrared ranges between wavelengths 3.5 and 2.0 micrometers and is produced by black bodies.

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For more on infrared radiation check out;

brainly.com/question/2369243

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