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3 years ago

A toothpaste contains sodium fluoride (NaF) What percentage of Fluoride is present.(4cs)

Chemistry

1 answer:

MariettaO [177]3 years ago

7 0

Answer:

45.2%

Explanation:

To calculate the percent of an element in a compound we divide the molar mass of the element by the compound and multiply that by 100

First lets find the molar mass of Fluoride

Looking at the periodic table Fluoride has a molecular mass of 18.998 g

Now we need to find the molecular mass of NaF

Looking at a periodic table, Sodium (Na) has a molecular mass of 22.990g and Fluoride has a molecular mass of 18.998 so NaF has a molecular mass of 22.990(1) + 18.998(1) = 41.988g

Now we divide the mass of fluoride by the mass of sodium fluoride and multiply that by 100 to find the percentage of fluoride that is present in NaF

Mass of Fluoride = 18.998g

Mass of Sodium Fluoride = 41.988g

Percentage of fluoride present in NaF = (18.998g / 41.988g) * 100 = 45.2%

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In the decomposition potassium nitride, 10.65 g of nitrogen form. How much potassium nitride was present initially ?

leonid [27]

Answer:

Mass = 99.8 g

Explanation:

Given data:

Mass of potassium nitride = ?

Mass of nitrogen produced = 10.65 g

Solution:

Chemical equation:

2K₃N→ 6K + N₂

Moles of nitrogen:

Number of moles = mass/ molar mass

Number of moles = 10.65 g / 28 g/mol

Number of moles = 0.38 mol

Now we will compare the moles of nitrogen with potassium nitride.

N₂ ; K₃N

1 : 2

0.38 : 2×0.38 =0.76

Mass of potassium nitride:

Mass = molar mass × number of moles

Mass = 131.3 g/mol × 0.76 mol

Mass = 99.8 g

7 0

4 years ago

If a patient\'s blood pressure is 145 over 65 mmHg, what is it in atmospheres (atm)

kicyunya [14]

Converting mmHg to atm is solved by division.

Example: Convert 745.0 to atm.

Solution- divide the mmHg value by the 760.0 mmHg / atm.

745 mmHg over 760.0 mmHg/atm

atm value is 0.980263

Now, I am a medical student and we have never had to convert a BP (blood pressure) to atm from mmHg, only ever kPA. SO, I am going to take a guess here and say that when you do the work to solve this, you are going to convert the Systolic (upper #) which is the 145. You should get 0.190789 and then convert the Diastolic (lower #) which is 65. You should get 0.08552632.

So your fraction so to speak should read, 0.190789/0.08552632 or 0.190789 over 0.08552632

(Just to note that is way to low of a BP, although it is irrelevant) Best wishes and good luck. "Remember, never just look for the right answer, look for why it is the right answer!"

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3 years ago

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Which of these is not a gas? hydrogen, oxygen, gravity, or helium

katrin2010 [14]

Answer:

I think that Gravity is not considered a gas but it can at the same time

Explanation:

Gasses are affected by gravity, as above video will prove. ... Yes, there is a attractive force between the gas molecules and gravity !

The rest are for sure gases

8 0

3 years ago

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A 6.165 gram sample of an organic compound containing C, H and O is analyzed by combustion analysis and 10.27 grams of CO2 and 3

e-lub [12.9K]

Answer:

Explanation:

mass of carbon in 10.27 g of CO₂ = 12 x 10.27 / 44 = 2.80 g

mass of hydrogen ( H ) in 3.363 g of H₂O = 2 x 3.363 / 18

= .373 g

These masses would have come from the sample of 6.165 g .

Rest of 6.165 g of sample is oxygen .

So oxygen in the sample = 6.165 - ( 2.8 + .373 ) = 2.992 g

Ratio of C , H , O in the sample

2.8 : .373 : 2.992

C: H : O : : 2.8 : .373 : 2.992

Ratio of moles

C: H : O : : 2.8/12 : .373/1 : 2.992 / 16

C: H : O : : .2333 : .373 : .187

C: H : O : : .2333/.187 : .373/.187 : .187/.187

C: H : O : : 1.247 : 1.99 : 1

C: H : O : : 5 : 8 : 4 ( after multiplying by 4 )

Hence empirical formula

C₅H₈O₄

Molecular formula ( C₅H₈O₄ )n

n ( 5 x 12 + 8 x 1 + 4 x 16 ) = 132

n x ( 60 + 8 + 64 ) = 132

n = 1

Molecular formula = C₅H₈O₄.

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3 years ago

Which of the following statements about C3 carbon fixation is true? a. C3 carbon fixation is an adaptation for plants exposed to

saul85 [17]

Answer: The answer is B

Explanation:

RiP BoZo. shout out to faze gabi staright up bopped potato girl.

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3 years ago

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