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tekilochka [14]
2 years ago
5

3. The air today is approximately one-fifth

Chemistry
1 answer:
Darina [25.2K]2 years ago
8 0

Answer: 40cm^3

Explanation:

Since the The air today is approximately one-fifth oxygen, the approximate volume of oxygen in 200cm3 of air would be:

= 1/5 × 200

= 40cm

The answer is 40cm^3

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Solid potassium chlorate decomposes upon heating to form
olga55 [171]

Answer:

32.6%

Explanation:

Equation of reaction

2KClO₃ (s) → 2KCl (s) + 3O₂ (g)

Molar mass of 2KClO₃ = 245.2 g/mol ( 122.6 × 2)

Molar volume of Oxygen at s.t.p = 22.4L / mol

since the gas was collected over water,

total pressure = pressure of water vapor + pressure of  oxygen gas

0.976 = 0.04184211 atm + pressure of oxygen gas at 30°C

pressure of oxygen = 0.976 - 0.04184211 = 0.9341579 atm = P1

P2 = 1 atm, V1 = 789ml, V2 = unknown, T1 = 303K, T2 = 273k at s.t.p

Using ideal gas equation

\frac{P1V1}{T1} = \frac{P2V2}{T2}

V2 = \frac{P1V1T2}{T1P2}

V2 = 664.1052 ml

245.2   yielded 67.2 molar volume of oxygen

0.66411 will yield = \frac{245.2 * 0.66411}{67.2}  = 2.4232 g

percentage of potassium chlorate in the original mixture = \frac{2.4232 * 100}{7.44} = 32.6%

3 0
3 years ago
Why is photosynthesis important for ecosystems everywhere
galina1969 [7]

it allows plants to survive  and continue to  reproduce

5 0
3 years ago
Read 2 more answers
A mixture of nacl and sucrose (c12h22o11) of combined mass 10.2 g is dissolved in enough water to make up a 250 ml solution. the
Vilka [71]
We use the osmotic pressure to determine the concentration of the solute in the solution. Then, we multiply the volume of the solution to determine the number of moles of solute particles. We need to establish to equations since we have two unknowns, the mass of of each solute. We do as follows:

osmotic pressure = CRT 
<span>C = 7.75 / 0.08205 (296.15) = 0.3189 mol / L</span>
<span>moles of particles = C*V = 0.3189*0.250 =0.0797 mol </span>
<span>0.0797 = moles of sucrose + 2*moles of salt </span>

<span>x + 2y = 0.0797 </span>
<span>and </span>
<span>x(MMsucrose) + y(MMNaCl) = 10.2</span>
<span>342x + 58.5y = 10.2
</span>
<span>solve for x and y
</span>
<span>x = 0.0252 mol sucrose</span>
<span>y = 0.0273 mol NaCl
 </span>
<span>mass Sucrose = 0.0252(342) = 8.6184 g </span>
<span>mass NaCl = 0.0273(58.5) = 1.5971 g </span>
<span>% NaCl = (1.5971 / 10.2)*100 = 15.66%</span>
4 0
3 years ago
Compute 6.28×1013+7.30×1011.
Simora [160]
6.28×1013+7.30×1011 this =13741.94
6 0
3 years ago
Which of the following measurements is used to measure the enthalpy of combustion? A. None of these B. Measuring the change in t
DaniilM [7]

Answer: Option (C) is the correct answer.

Explanation:

In a substance, the total energy of its molecular motion is known as heat. Whereas when we measure the average energy of molecular motion of a substance then it is known as temperature.

So, any increase or decrease in temperature will lead to change in heat of a substance.

When one mole of a substance is burned then the amount of energy released  in the form of heat is known as heat of combustion.

Relation between heat and temperature is as follows.

                    q = m \times C \times \Delta T

Thus, we can conclude that to measure the enthalpy of combustion it cannot be measured, only calculated using the equation; q = mc \Delta T.

4 0
3 years ago
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