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3 years ago

Why is helium considered as a noble gas

2 answers:

7 0

Noble gases are known for having a full outer shell of electrons which helium has as it has two electrons its first electron shell is completely filled

larisa [96]3 years ago

3 0

Helium is considered a noble gas because it has 8 valence electrons, as well as it also is a stable element. Meaning that it consists of a full octet.

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Classify the same processes as exothermic or endothermic.

Inessa [10]

Answer:

1.endothermic

2.exothermic

3.exothermic

8 0

3 years ago

Read 2 more answers

A flask with a volume of 3.16 l contains 9.33 grams of an unknown gas at 32.0°c and 1.00 atm. What is the molar mass of the gas?

Inessa05 [86]

Answer:

73.88 g/mol

Explanation:

For this question we have to keep in mind that the unknown substance is a gas, therefore we can use the ideal gas law:

$PV=nRT$

In this case we will have:

P= 1 atm

V= 3.16 L

T = 32 ªC = 305.15 ºK

R= 0.082 $\frac{atm*L}{mol*K}$

n= ?

So, we can solve for "n" (moles):

$1~atm*3.16~L~=~n*0.082~\frac{atm*L}{mol*K}*305.15~K$

$n=\frac{1~atm*3.16~L~}{0.082~\frac{atm*L}{mol*K}*305.15~K}$

$n=0.126~mol$

Now, we have to remember that the molar mass value has "g/mol" units. We already have the grams (9.33 g), so we have to divide by the moles:

$molar~mass=\frac{9.33~grams}{0.126~mol}$

$molar~mass=73.88\frac{grams}{mol}$

7 0

3 years ago

Determine what type of compound is shown below:

34kurt

Answer:

Polar

Explanation:

Methanol is not electrostatic

It's not metallic as it has no metals in it

It's not ionic as coordinate bonding is made.

It's polar as a lone pair is present over OH-

3 0

2 years ago

Consider the reaction. mc014-1.jpg How many grams of methane should be burned in an excess of oxygen at STP to obtain 5.6 L of c

garri49 [273]

The reaction for the combustion of methane can be expressed as follows.
CH4 + 2O2 --> CO2 + 2H2O
We solve first for the amount of carbon dioxide in moles by dividing the given volume by 22.4L which is the volume of 1 mole of gas at STP.
moles of CO2 = (5.6 L) / (22.4 L/1 mole)
moles of CO2 = 0.25 moles
Then, we can see that every mole of carbon dioxide will need 1 mole of methane
moles methane = (0.25 moles CO2) x (1 moles O2/1 mole CO2)
= 0.25 moles CH4
Then, multiply this by the molar mass of methane which is 16 g/mole. Thus, the answer is 4 grams methane.

5 0

3 years ago

Read 2 more answers

Refer to the two formulas for xylose.

Ludmilka [50]

Answer:

A is the molecular formula for xylose because shows the actual number of atoms in the compound: Formula B is the empirical formula for xylose because it shows the smallest whole-number ratio for the different atoms in the compound: Formula A is the molecular formula for xylose because shows the arrangement of atoms in the compound: Formula B is the structurab formula for xylose because it shows the smallest whole-number ratio for the different atoms in the compound: Formula A is the empirical formula for xylose because it shows the actual number of atoms in the compound: Formula B is the molecular formula for xylose because it shows the smallest whole-number ratio for the different atoms in the compound: Formula A is the structural formula for xylose because it shows the arrangement of atoms in the compound: Formula B is the empirical formula for xylose because it shows the smallest whole-number ratio for the different atoms in the compound.

5 0

2 years ago