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Mamont248 [21]
3 years ago
6

The molecular formula for caffeine is C8H10N4O2. Which of the following elements is not found in caffeine? carbon helium nitroge

n oxygen
Chemistry
2 answers:
slavikrds [6]3 years ago
8 0

Answer:

Helium

Explanation:

LOOK AT THE TABLE OF ELEMENTS WOMAN!!!

Rudik [331]3 years ago
5 0

Answer:

Helium

Explanation:

When looking at the formula, you see the elements Carbon (C), Hydrogen (H), Nitrogen (N) and Oxygen (O). Helium is He, which is not shown in the formula.

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Answer:

1.what I observe.

Explanation:

The dependent variable in an experiment is what is being observed in the experimental procedure.

This variable is the one that is closely tied to the effects originating from changing the independent variables.

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A 3.31-g sample of lead nitrate, Pb(NO3)2, molar mass = 331 g/mol, is heated in an evacuated cylinder with a volume of 2.53 L. T
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Answer:

0.486atm is the pressure of the cylinder

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1 mole of Pb(NO₃)₂ descomposes in 4 moles of NO2 and 1 mole of O2. That is 1 mole descomposes in 5 moles of gas.

To find the pressure of the cylinder, we need to find moles of gas produced, and using general gas law we can determine the pressure of the gas:

<em>Moles Pb(NO₃)₂ and moles of gas:</em>

3.31g * (1mol / 331g) = 0.01 moles of Pb(NO₃)₂.

That means moles of gas produced is 0.05 moles.

<em>Pressure of the gas:</em>

Using PV = nRT

P = nRT/V

<em>Where P is pressure (Incognite)</em>

<em>V is volume (2.53L)</em>

<em>R is gas constant (0.082atmL/molK)</em>

<em>T is absolute temperature (300K)</em>

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P = 0.05mol*0.082atmL/molK*300K / 2.53L

P = 0.486atm is the pressure of the cylinder

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3 years ago
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