In general, the nucleus of a small atom is stable. Therefore, over very short distances, such as those in a small nucleus,

A sample of an unknown compound with a mass of 0.847 g has the following composition: 50.51 % fluorine and 49.49 % iron. When th

sergejj [24]

Answer: 0,4278g of F and 0,4191g of Fe

Explanation: it's possible to calculate the mass of each element by multiplying the percentage (decimal) of the element by the mass of the compound.

For Fluorine (F)

0,847g * 0,5051 = 0,4278g of F

For iron (Fe)

0,847 * 0,4949 = 0,4191g of Fe

This is determined because even when the compound is decomposed, due to conservative law of mass, the decomposition process do not affect the amount of matter, so the mass of the elements remain even if they are separated from the original molecule.

At the end, the sum of the elements masses should be the total mass of the compound.

4 0

2 years ago

Read 2 more answers

Find the enthalpy of neutralization of HCl and NaOH. 87 cm3 of 1.6 mol dm-3 hydrochloric acid was neutralized by 87 cm3 of 1.6 m

Vesna [10]

Answer : The correct option is, (A) -101.37 KJ

Explanation :

First we have to calculate the moles of HCl and NaOH.

$\text{Moles of HCl}=\text{Concentration of HCl}\times \text{Volume of solution}=1.6mole/L\times 0.087L=0.1392mole$

$\text{Moles of NaOH}=\text{Concentration of NaOH}\times \text{Volume of solution}=1.6mole/L\times 0.087L=0.1392mole$

The balanced chemical reaction will be,

$HCl+NaOH\rightarrow NaCl+H_2O$

From the balanced reaction we conclude that,

As, 1 mole of HCl neutralizes by 1 mole of NaOH

So, 0.1392 mole of HCl neutralizes by 0.1392 mole of NaOH

Thus, the number of neutralized moles = 0.1392 mole

Now we have to calculate the mass of water.

As we know that the density of water is 1 g/ml. So, the mass of water will be:

The volume of water = $87ml+87ml=174ml$

$\text{Mass of water}=\text{Density of water}\times \text{Volume of water}=1g/ml\times 174ml=174g$

Now we have to calculate the heat absorbed during the reaction.

$q=m\times c\times (T_{final}-T_{initial})$

where,

q = heat absorbed = ?

$c$ = specific heat of water = $4.18J/g^oC$

m = mass of water = 174 g

$T_{final}$ = final temperature of water = 317.4 K

$T_{initial}$ = initial temperature of metal = 298 K

Now put all the given values in the above formula, we get:

$q=174g\times 4.18J/g^oC\times (317.4-298)K$

$q=14110.008J=14.11KJ$

Thus, the heat released during the neutralization = -14.11 KJ

Now we have to calculate the enthalpy of neutralization.

$\Delta H=\frac{q}{n}$

where,

$\Delta H$ = enthalpy of neutralization = ?

q = heat released = -14.11 KJ

n = number of moles used in neutralization = 0.1392 mole

$\Delta H=\frac{-14.11KJ}{0.1392mole}=-101.37KJ/mole$

Therefore, the enthalpy of neutralization is, -101.37 KJ

3 0

2 years ago

Consider the dissolution of MnS in water (Ksp = 3.0 × 10–14). MnS(s) + H2O(l) Mn2+(aq) + HS–(aq) + OH–(aq) How is the solubility

Mademuasel [1]

Answer:

The solubility of MnS will decrease on addition of KOH solution.

Explanation:

As per the equation given:

$MnS(s)+H_{2}O(l) -->Mn^{+2}(aq)+HS^{-}(aq)+OH^{-}(aq)$

On dissolution of MnS in water it gives a basic solution as it gives hydroxide ions.

Now when the we are adding aqueous KOH solution, it will dissociate as:

$KOH(aq)--->K^{+}(aq)+OH^{-}(aq)$

Thus it will further furnish more hydroxide ion,

This will increase the concentration of hydroxide ions (present of product side), the system will try to decrease its concentration by shifting towards reactant side.

Thus the solubility of MnS will decrease on addition of KOH solution.

7 0

2 years ago

How many moles of FeS2 are required to produce 32g of SO2?

nirvana33 [79]

Answer:

<u>So, the right answer is</u>

No. of moles of FeS₂ = 0.25 mole

Explanation:

From the balanced

4 FeS2 + 11 O2 → 2 Fe2O3 + 8 SO2

it is clear that 4 mol FeS₂ react with O₂ to give Fe₂O₃ and 8 mol of SO₂

First, we have to convert mass of SO₂ into No. of moles as following:

SO₂ has molar mass = 64 g/mol

No. of moles of SO₂ = (mass / molar mass) = (32 g / 64 g/mol) = 0.5 mol

we know that

4 mol FeS₂ gives→ 8 mol of SO₂

1 mol FeS₂ gives→ 2 mol of SO₂

??? mol FeS₂ gives→ 0.5 mol of SO₂

No. of moles of FeS₂ = (0.5 mol * 1 mol ) / 2 mol = 0.25 mol

<u>So, the right answer is</u>

No. of moles of FeS₂ = 0.25 mol

7 0

2 years ago

What is the total number of sp2-hybridized carbon atoms present in the fluorophore used in the experiments

Mandarinka [93]

Answer:

9

Explanation:

The structure of fluorophore used in the experiments has been drawn in the attachment. And from the drawing counting we can say that there are 9 sp2-hybridized carbon atoms present. Fiuorophores are a fluorescent chemical compound that can re-emit light upon light excitation. Normally used to produce absorbance and emission spectra.

3 0

2 years ago