1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
emmainna [20.7K]
3 years ago
12

A student thermally decomposed a 0.150 gram sample of impure potassium chlorate. Manganese dioxide was used as a catalyst in the

reaction. The student collected 43.60 mL of oxygen gas over water in a eudiometer. Potassium chloride was the other product of the reaction. The temperature and pressure at collection time were 20.00 oC and 762.10 mm Hg respectively. The water level in the eudiometer was 4.22 cm below the outside water level in the beaker.
1) What is the corrected pressure of the dry oxygen gas?
2) What is the volume in mL, of the dry oxygen gas at STP conditions?
3) How many molecules of oxygen were collected?
4) what is the percent purity of the original potassium chlorate sample?
Chemistry
1 answer:
harkovskaia [24]3 years ago
5 0

Answer:

1. Vapor pressure of dry oxygen gas = 747.68 torr

2. Volume at STP = 39.97 mL

3. Number of oxygen gas molecules = 1.074 × 10²¹ molecules

4. Percent purity of KClO3 = 97.3 %

Explanation:

The balanced equation for the reaction is given below :

2 KClO3 (s) ------> 2 KCl (s) + 3 O2 (g)

1) Since the water level in the eudiometer was below the outside water level in the beaker,

Vapor pressure of dry oxygen gas = Total pressure + pressure due to difference in water levels - vapor pressure of water

Vapor pressure of water at 20 °C is 17.535 mm (torr).

Pressure due to difference in water level = 4.22 cm × 10mm/cm / 13.534 (13.534 is the density of mercury) = 3.118 mm (torr).

Vapor pressure of dry oxygen gas = 762.10 torr + 3.118 torr - 17.535 torr

Vapor pressure of dry oxygen gas = 747.68 torr

2) P₁ = 747.68 torr; V₁ = 43.60 ml; T1 = 20 °C + 273.15 = 293.15 K

P₂ = 760 torr; T₂ = 273.15 K; V₂ = ?

Using the general gas equation = P₁V₁/T₁ = P₂V₂/T₂

V2₂= P₁V₁T₂ / P₂T₁

V₂ = (747.68 × 43.60 × 273.15 ) / (760 × 293.15)

V₂ = 39.97 ml

Volume of dry oxygen gas at STP = 39.97 mL

3) Volume of oxygen gas at STP 39.97 mL = 0.03997 L

Number of moles of oxygen gas in 0.03997 L = volume of gas at STP /molarvolume at STP

Number of moles of oxygen gas = 0.03997/22.4 L

Number of molecules of oxygen gas = 0.03997/22.4 L × 6.03 × 10²³ molecules

Number of oxygen gas molecules = 1.074 × 10²¹ molecules

e) Number of moles of oxygen gas = 0.03997/22.4 = 0.001784 moles

From the equation, mole ratio of oxygen gas and potassium chlorate is 3 : 2

Moles KClO3 = 2/3 × 0.001784 moles = 0.001189 moles

Molar mass of KClO3 = 39 + 35.5 + 3 × 16 = 122.5 g

Actual mass of KClO3 decomposed = 122.5 grams × 0.001189 mole = 0.146 grams

Percent purity = (actual mass KClO3 decomposed / sample mass of impure KClO3) × 100%

Percent purity = (0.146/0.150) × 100% = 97.3 %

You might be interested in
PLEASE HELP!! <br> this is on USAtestprep <br> a)<br> b)<br> c)<br> d)
kaheart [24]
The answer is D!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
3 0
2 years ago
what is the oxidation state of each element in coh2? c o h what is the oxidation state of each element in febr3? fe br
fgiga [73]

The oxidation state of the elements  in the compounds are:

CoH₂:

  • Co = +2
  • H = -1

FeBr₃:

  • Fe = +3
  • Br = -1

<h3>What is the oxidation states of the elements in the given compounds?</h3>

The oxidation states of the elements in each of the given compounds is determined as follows:

Cobalt dihydride, CoH₂

Co = +2

H = -1

Iron (iii) bromide, FeBr₃

Fe = +3

Br = -1

In conclusion, the oxidation state of the elements are charges they have in the compound.

Learn more about oxidation state at: brainly.com/question/27239694

#SPJ1

8 0
2 years ago
MgO + H2O = Mg(OH)2 is an example of a _____ chemical reaction.
algol [13]

a) synthesis- or combination- reaction

3 0
3 years ago
Please help me................I beg you.........
Finger [1]

Answer:

the problem is that Gary is not the smartest snail.the hypothesis is that he thinks he can get smarter by eating super snail food everyday.

hope this helps

5 0
3 years ago
Describe how the properties of elements in the same group differ to the properties of elements in the same period
Fofino [41]

Answer:

(a) (i) All the elements of a group have similar chemical properties because they have same no. of valence electrons in their outermost shell. (ii) All the elements of a period have different chemical properties because they have different no. of valence electrons in their atoms.

5 0
3 years ago
Other questions:
  • The [H3O+] concentration in the rainwater of pH = 4.35 is:
    14·1 answer
  • Which of the following is not a concentration unit (a) 1 molar (b) 1 equivalent (c) 1% by mass (d) 1 molal
    6·1 answer
  • Solutions of hydrochloric acid caused the light bulb to glow brighter than solutions of acetic acid. how do you account for the
    14·1 answer
  • Which planet likely has flowing liquid metallic hydrogen as a source of its magnetic field?
    11·2 answers
  • How is the tempature related to phsyical change
    10·1 answer
  • Why is a liquid able to flow?
    6·2 answers
  • Mr. Watson's students brought him a cake on his birthday because he was their favorite teacher. Before he blew out the candles,
    14·2 answers
  • Which formula represents a convalent compound<br><br><br>. H2O2<br><br>.CaO<br><br>.MgS<br><br>.NaCl
    14·2 answers
  • Choose the statement below that correctly describes electrons.
    8·1 answer
  • Help, please <br> I will mark the brainliest answer if right!
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!