Chemistry, 21.07.2019 03:31 Qpaoswp34

When a 30.98-g sample of phosphorus reacts with oxygen, a 71.00-g sample of phosphorus oxide is formed. what is the percent composition of the compound? what is the empirical formula for this compound?

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Answer from: jourdyno

- P = 43.63% and O = 56.37% and the empirical formula is P_2O_5

Solution:- mass of Phosphorous = 30.98 g

mass of product(phosphorous oxide) = 71.00 g

mass of oxygen = 71.00 - 30.98 = 40.02 g

percentage of phosphorous in the compound = (30.98/71.00)100 = 43.63%

percentage of oxygen in the compound = (40.02/71.00)100 = 56.37%

moles of P = 30.98 g x ( 1mol/30.97 g) = 1.00 mol

moles of O = 40.02 g x (1 mol/ 16.00 g) = 2.50 mol

Ratio of moles of P to O is 1.00:2.50

The whole number ratio is 2:5

So, the empirical formula of the phosphorous oxide formed is P_2O_5

Answer from: Monicaamm12983

Answer : The percent composition of P = 43.63 % and O = 53.37 % .

Empirical formula of Phosphorous oxide = P₂O₅

Part A : Percent composition :

It is percent of each element present in compound . It is given by formula :

$Percent composition = \frac{mass of element}{ total mass of compound } * 100$

Given : Mass of Phosphorous (P ) = 30.98 g

Mass of Compound Phosphorous oxide = 71.00 g

Mass of Oxygen (O) = mass of compound - mass of P

= 71.00 g - 30.98 g = 40.02 g

$Percent composition of P = \frac{mass of P }{ mass of compound}$ $= \frac{30.98 g }{71.00 g} * 100$

Percent composition of P = 43.63 %

$Percent composition of O = \frac{mass of Al}{Mass of compound } * 100 = \frac{40.02 g }{71.00 g} * 100$

Percent composition of O = 53.37 %

Part B : Empirical formula of Phosphorous Oxide.

Empirical formula is formula which shows the proportion of element present in a compound . Following are the steps to calculate empirical formula of an compound :

Step 1 : Find masses of each element .

Mass of P = 30.98 g

Mass of O = 40.02 g

Step 2 : Conversion of masses of element to its mole .

$Mole = \frac{mass }{molar mass }$

Given : Mass of P = 30.98 g $Molar mass of P = 30.97 \frac{g}{ mol}$

$Mole of P = \frac{30.98 g }{30.97\frac{g}{mol} } = 1 mol$

Given: Mass of O = 40.02 g $Molar mass of O = 15.99\frac{g}{mol}$

$Mole of O = \frac{40.02 g}{15.99\frac{g}{mol}} = 2.5 mol$

Step 3 : Finding Ratio of mole .

In this step ratio is found by dividing each mole by smallest mole .Since mole of P is smaller , so this will be used for division.

$Ratio of mole of P= \frac{mole of P }{mole of P } = \frac{1 mol}{1 mol} = 1$

$Ratio of mole of O = \frac{ mole of O }{mole of P } = \frac{2.5 }{1 } = 2.5$

Hence , Ratio of P : O = 1 : 2.5

Since the ratio is in fraction , it need to be converted to whole number . So we multiply the ratio by such a minimum number which gives us a whole number ratio. This step is skipped if the ratio already comes in whole number.

On multiplication the ratio by 2 :

Ratio of P : O = ( 1 : 2.5 ) * 2 = 1 * 2 : 2.5 * 2

Ratio of P : O = 2 : 5

Step 4 : Writing the empirical formula

The ratio of P and O is 2: 5 , which gives the empirical formula of compound as P₂O₅ .

Answer from: Quest

Ais your answer to this

Answer from: Quest

Note that 2 mol dm⁻³ = 2 mol/(dm³)outline: we're given the concentration of hcl, which is 2 mol dm⁻³ (cubic meters in the denominator can represent volume, so i know this is concentration). we're an amount of calcium carbonate caco₃, which is 5 g. we're presented with a chemical equation which includes caco₃ and hcl. we are told to find the volume of hcl. from what we see so far, this seems to be a stoichiometry problem. we'll have to use the given information about calcium carbonate to find the amount of moles of hcl needed to fully react with calcium carbonate. then we'll have information about the moles of hcl and the concentration of hcl; that will be enough to figure out volume according to the formula concentration = moles / volume.======all the answer choices are not in dm.convert the given concentration so that it uses cm⁻³.we can use conversion factors. we have to cube our conversion factors so that dimensional analysis works.we can convert to meters first, using the fact that 10 dm = 1 m ⇔ 10³ dm³ = 1 m³then we use the fact that 10² cm = 1 m ⇔ (10² cm)³ = (1 m)³ ⇔ 10⁶ cm³ = 1 m³so converting: $\dfrac{\text{2 mol}}{\text{dm}^{3}} \cdot \dfrac{\text{10}^3\text{ dm}^3}{\text{1 m}^3} \cdot \dfrac{\text{1 m}^3}{10^6\text{ cm}^3} \\ \\ = \dfrac{\text{2 mol}}{1} \cdot \dfrac{\text{10}^3}{1} \cdot \dfrac{1}{10^6\text{ cm}^3} \qquad \text{\footnotesize cancelling units} \\ \\ = \dfrac{2\text{ mol}}{10^3 \text{ cm}^3} \\ \\ = 0.002\text{ mol/cm}^3$ now we have to find the moles of hydrochloric acid neededfind the moles of calcium carbonate. we have to find the molar mass of calcium carbonate, caco₃, which can be found by molar mass = (mass ca) + (mass c) + 3(mass o) = 40 + 12 + 3(16) = 100 g/molconvert the given 5 g to moles: mol caco₃ = 5 g caco₃ * 1 mol/(100 g) = 0.05 mol caco₃use stoichiometry (ratios) to figure out the moles of hcl needed. ratio wise, there's 2 hcls for every caco₃, so use dimensional analysis mol hcl = mol caco₃ * (2 mol hcl) / (1 mol caco₃) = 0.05 mol hcl * 2 = 0.1 mol hcl we have 0.1 mol hcl and concentration of hcl (0.002 mol/cm³).we need to find volumesince concentration = moles / volume, rearrange to get volume = moles / concentration volume = 0.1 mol / (0.002 mol/cm³) volume = 50 cm³

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When a 30.98-g sample of phosphorus reacts with oxygen, a 71.00-g sample of phosphorus oxide is form...

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