All of the noble gasses have 8 valence electrons except _____. helium argon xenon neon this is science

Chemistry

2 answers:

pogonyaev3 years ago

5 0

<span>Helium is the noble gas with only 2 valence electrons

I Hope This helps

</span>

Tomtit [17]3 years ago

5 0

Helium because it has 2 electrons
just like the photo

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How many grams of CaF2 would be needed to produce 1.23 moles of F2?

NemiM [27]

We see from the chemical formula itself that there is 1 mole of F2 for every 1 mole of CaF2, hence the number of moles of CaF2 is also:

moles CaF2 = 1.23 moles

The molar mass of CaF2 is 78.07 g/mol, so the mass is:

mass CaF2 = 78.07 g / mol * 1.23 mol

<span>mass CaF2 = 96.03 grams</span>

5 0

3 years ago

Calculate the ph of a 0.40 m solution of sodium benzoate (nac6h5coo) given that the ka of benzoic acid (c6h5cooh) is 6.50 x 10-5

asambeis [7]

Hello!

The dissociation reaction for Benzoic Acid is the following:

C₆H₅COOH + H₂O ⇄ C₆H₅COO⁻ + H₃O⁺

The Ka expression is the following and we clear for the concentration of H₃O⁺(X) assuming that the dissociation is little so we can rule it out in the denominator of the equation:

$Ka= \frac{[C_6H_5COO^{-}]*[H_3O^{+}] }{[C_6H_5COOH]}=\frac{X*X }{0,40 -X} (assume: 0,40-X\approx0,40)\\ \\ X= \sqrt{0,40*6,50*10^{-5} }=0.00510M \\ \\ pH=-log([H_3O^{+}]=2,29$

So, the pH of this Benzoic Acid solution is 2,29

Have a nice day!

3 0

3 years ago

Which of the statements are true? Triacylglycerols (triglycerides) are carboxylic acids. Fats that contain more unsaturated fatt

astraxan [27]

<h2>The correct answer is given below:</h2>

Explanation:

Fats or lipid can be defined as high energy containing organic macro-molecules.
The basic molecule which makes up fat or lipid is Triacylglycerol.
A Triacylglcerol molecule is made up of one molecule of glycerol attached to three fatty acids molecules.
Here, the carboxylic acid groups of three fatty acid molecules are attached with the help of ester bonds to the three hydroxyl groups of one glycerol molecule.
Fatty acids are of two types, Saturated and Unsaturated.
Saturated fatty acid molecules can be defined as those in which the carbon atoms forming the hydrocarbon chain of the fatty acid molecule are linked to each other by single covalent bonds. The structure of saturated fatty acid molecule is linear or straight.
Unsaturated fatty acid molecules can be defined as those in which there are presence of one or multiple double covalent bonds in between the carbon atoms forming the hydrocarbon chain of the fatty acid molecule.
These double bonds in unsaturated fatty acid molecules form kinks or bend in the structure of the fatty acid .
In lipid or fat, the fatty acid molecules associate with each other by hydrophobic or Van der Waals forces of interactions.
In saturated fat, due to the linear structure of the fatty acids, the fatty acid molecules associate close to each other thereby forming a compact fat molecule with high melting point. This causes them become solidified at room temperature.
In unsaturated fat, the presence of kinks or bends in the fatty acid molecules results in the generation of fat molecules whose structure is not compact due to the presence of spaces in between the fatty acid molecules. These fats have a lower melting point which causes them to be liquid at room temperature.
The first statement is FALSE as triacylglycerols are formed by the esterification of three molecules of fatty acids with one molecule of glycerol.
The second statement is TRUE as unsaturated fatty acids have lower melting point than saturated fatty acids.
The third statement is FALSE as saturated fats have higher melting point than unsaturated fats.
The fourth statement is TRUE as triacylglycerols are formed by the esterification of three molecules of fatty acids with one molecule of glycerol.
The fifth statement is TRUE as unsaturated fats have lower melting point and so they are liquid at room temperature.

7 0

3 years ago

Use the combustion of methanol to calculate

sergey [27]

Answer:

4.18 kJ / 6.55x10-3 mol = 638.6 kJ/mol = experimental ΔHC kJ/mol methanol.

Explanation:

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3 years ago

Distance divided by time

son4ous [18]

150÷3=50

350÷4=87.5

(50+87.5)÷2

137.5÷2

=68.75

4 0

3 years ago