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3 years ago

What is the mass of 12.3 moles of helium (He)?

Chemistry

1 answer:

anzhelika [568]3 years ago

6 0

Answer : The mass of 12.3 moles of helium (He) is, 49.2 grams.

Solution : Given,

Moles of helium = 12.3 moles

Molar mass of helium = 4 g/mole

Formula used :

$\text{Mass of helium}=\text{Moles of helium}\times \text{Molar mass of helium}$

$\text{Mass of helium}=(12.3mole)\times (4g/mole)=49.2g$

Therefore, the mass of 12.3 moles of helium (He) is, 49.2 grams.

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What does the root “thermal” mean?<br> Please Help<br> I will give you Brainliest

Nezavi [6.7K]

Answer:

If it has to do with heat, it's thermal. ... The Greek word therme, meaning “heat,” is the origin of the adjective thermal. Something that is thermal is hot, retains heat, or has a warming effect.

Explanation:

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2 years ago

Harvey kept a balloon with a volume of 348 milliliters at 25.0˚C inside a freezer for a night. When he took it out, its new volu

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Initial volume of the balloon = $V_{1}$ = 348 mL

Initial temperature of the balloon $T_{1}$ = $25.0^{0}C + 273 = 298 K$

Final volume of the balloon $V_{2}$ = 322 mL

Final temperature of the balloon = $T_{2} = ?$

According to Charles law, volume of an ideal gas is directly proportional to the temperature at constant pressure.

$\frac{V_{1} }{T_{1} } =\frac{V_{2} }{T_{2} }$

On plugging in the values,

$\frac{348mL}{298 K} =\frac{322 mL}{T_{2} }$

$T_{2} =276 K$

Therefore, the temperature of the freezer is 276 K

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2 years ago

The decomposition of dinitrogen pentoxide, N2O5, to NO2 and O2 is a first-order reaction. At 60°C, the rate constant is 2.8 × 10

Sati [7]

Answer:

a. 113 min

Explanation:

Considering the equilibrium:-

2N₂O₅ ⇔ 4NO₂ + O₂

At t = 0 125 kPa

At t = teq 125 - 2x 4x x

Thus, total pressure = 125 - 2x + 4x + x = 125 - 3x

125 - 3x = 176 kPa

x = 17 kPa

Remaining pressure of N₂O₅ = 125 - 2*17 kPa = 91 kPa

Using integrated rate law for first order kinetics as:

$[A_t]=[A_0]e^{-kt}$

Where,

$[A_t]$ is the concentration at time t

$[A_0]$ is the initial concentration

Given that:

The rate constant, k = $2.8\times 10^{-3}$ min⁻¹

Initial concentration $[A_0]$ = 125 kPa

Final concentration $[A_t]$ = 91 kPa

Time = ?

Applying in the above equation, we get that:-

$91=125e^{-2.8\times 10^{-3}\times t}$

$125e^{-2.8\times \:10^{-3}t}=91$

$-2.8\times \:10^{-3}t=\ln \left(\frac{91}{125}\right)$

$t=113\ min$

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2 years ago

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Alika [10]

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3 years ago

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aniked [119]

Answer:

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Explanation:

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3 years ago