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2 years ago

How many HNO3 molecules are in 4.20 grams?

Chemistry

1 answer:

qaws [65]2 years ago

6 0

Answer: 4.01x 10 ²² molecules HNO3

Explanation: Solution attached:

Convert mass of HNO3 to moles using its molar mass.

Convert moles of HNO3 to molecules using the Avogadro's number

4.20 g HNO3 x 1 mole HNO3 / 63 g HNO3 x 6.022x10²³ molecules HNO3 / 1 mole HNO3

= 4.0X 10 ²² molecules HNO3

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How many moles of gas Does it take to occupy 520 mL at a pressure of 400 torr and a temperature of 340 k

Ann [662]

Answer would be B. I provided work on an image attached. Message me if u have any other questions on how to do it

6 0

2 years ago

in a candy factory, the nutty chocolate bars contain 22.0% by mass pecans. If 5.0 kg of pecans were used for candy last Tuesday,

zysi [14]

22.0 is the same as saying that in 100 grams of a chocolate bar, there are 22.0 grams of pecans. or to make it easier because of this problem- 100 Kilograms of a chocolate bar, there is 22.0 Kg of pecans. we can use this as a conversion factor (what is used to convert a value to another value.

conversion factor---> 22.0 kg of pecan= 100 kg of chocolate bar
Note: remember this, what you are converting from goes in the denominator, what you converting to goes in the numerator.

5.0 Kg of pecan (100 Kg of chocolate bar/ 22.0 Kg of pecan)= 23 Kg of chocolate bar

7 0

2 years ago

Cyclohexane has a freezing point of 6.50 ∘C and a Kf of 20.0 ∘C/m. What is the freezing point of a solution made by dissolving 0

ExtremeBDS [4]

Answer:

The freezing point will be $2.9^{0}C$

Explanation:

The depression in freezing point is a colligative property.

It is related to molality as:

$Depressioninfreezing point=K_{f}Xmolality$

Where

Kf= $20\frac{^{0}C}{m}$

the molality is calculated as:

$molality=\frac{moles_{solute}}{mass_{solvent}}$

$moles=\frac{mass}{molarmass}=\frac{0.694}{154}=0.0045mol$

$massofcyclohexane=25g=0.025Kg$

$molarity=\frac{0.0045}{0.025}=0.18m$

Depression in freezing point = $20X0.18=3.6^{0}C$

The new freezing point = $6.5^{0}C-3.6^{0}C=2.9^{0}C$

5 0

2 years ago

A chemical engineer must report the average volume of a certain pollutant produced by the plants under her supervision. Here are

AfilCa [17]

Answer:

The chemical engineer should report average volume of 15.34 L.

Explanation:

Volume of Macon = 0.519 L

Volume of Allegheny = 44.67 L

Volume of Doheny = 0.826 L

Average of the volume of the pollutants:

$\frac{0.519 L+44.67 L+ 0.826L}{3}=\frac{46.015 L}{3}=15.33833 L$

The rule apply for the addition and subtraction is :

The least precise number present after the decimal point determines the number of significant figures in the answer.

Here the 44.67 has two significant digit after decimal point.So the answer will be reported as in with 2 significant figures after decimal point.

$15.33833 L\approx 15.34 L$

The chemical engineer should report average volume of 15.34 L.

5 0

2 years ago

Methane and ethane are both made up of carbon and hydrogen. In methane, there are 12.0 g of carbon for every 4.00 g of hydrogen,

Sati [7]

Answer:

The answer is: Law of multiple proportions

Explanation:

The law of multiple proportions is a law of chemical combination given by Dalton in 1803.

According to this law, if more than one chemical compound is formed by combining two elements, then the mass of an element that combines with the fixed mass of other element is represented in the form of small whole number ratio.

<u>Therefore, is an illustration of the law of the law of multiple proportions.</u>

8 0

2 years ago