This is a ___________ gibbous moon. A) crescent B) new C) waning D) waxing

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

harkovskaia [24]

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 %

5 0

4 years ago

how do i caculate the trmperature change that 725 grams of aluminum will undergo when 2.35x10^4 Joules of thermal energy are add

sesenic [268]

Answer:

36°C

Explanation:

Given parameters:

Mass of aluminum = 725g

Quantity of heat = 2.35 x 10⁴J

Unknown:

Temperature change = ?

Solution:

To solve this problem, we simply use the expression below:

The quantity of energy is given as:

Q = m C Δt

Q is the quantity of energy

m is the mass

C is the specific heat capacity of aluminum = 0.9J/g°C

Δt is the change in temperature

The unknown is Δt;

Δt = $\frac{Q}{mc}$ = $\frac{2.35 x 10^{4} }{725 x 0.9}$ = 36°C

4 0

3 years ago

What kind of adaptation are the ears on a rabbit

Jet001 [13]

Answer:

Structural

Explanation:

Structural adaptions are the physical features of an organism that enable them to survive in their environment.

The rabbit’s long ears are an essential survival tool. They help the rabbit listen to the faint sounds made by nearby predators and their shape helps to detect sound direction accurately.

Also, if the rabbit lives in a hot desert, the large ears radiate heat, allowing it to control its temperature.

8 0

3 years ago

What happens to an atom when it gains an electron?

jasenka [17]

I'm pretty sure it becomes an ion! If an atom gains a negative electron, it becomes an ion.

6 0

3 years ago

Read 2 more answers

If u can help answer these questions i’ll mark you brainliest, pls it’s due tomorrow

AveGali [126]

Explanation:

First Question:

The equation is given as;

2KClO3 --> 2KCl + 3O2

2 mol of KClO3 produces 2 mol of KCl

Converting 7.6 g of KCl to mol;

Number of moles = Mass / Molar mass = 7.6 / 74.5513 = 0.1019

2 mol = 2 mol

x mol = 0.1019

solving for x;

x = 0.1019 mol of KClO3

converting to mass;

Mass = Number of mol * Molar mass = 0.1019 * 122.55 = 12.48

Correct option = B. 12.5 g

Second Question

The equation is given as;

1N2 + 3H2 --> 2NH3

3 mol of H2 produces 2 mol of NH3

Converting 34.06g of NH3 to mol;

Number of moles = Mass / Molar mass = 34.06 / 17.031 = 2 mol

3 mol = 2 mol

x mol = 2 mol

Solving for x;

x = 6 / 2 = 3 mol of H2

Converting 3 mol H2 to g;

Mass = Number of moles * Molar mass = 3 * 2.016 = 6.048g

Correct option: B. 6.05g

3 0

3 years ago