General Chemistry Answers

A student in your Chemistry class tells you that Nitrogen-14 and nitrogen-15 are not isotopes because they have the same number of protons. How would you refute this statement?

A typical human cell is approximately 11.00μm

11.00μm in diameter and enclosed by a membrane that is 5.00 nm

5.00 nm thick.

What is the total volume 𝑉

V of the cell, including the membrane? To simplify the calculations, model the cell as a sphere.

𝑉=

V=

μm

3

μm3

What is the volume 𝑉

membrane

Vmembrane of the cell membrane?

𝑉

membrane

=

Vmembrane=

μm

3

μm3

What percentage 𝑃

membrane

Pmembrane of the total volume does the membrane occupy?

A liquid solvent is added to a flask containing an insoluble solid. The total volume of the solid and liquid together is 75.0 mL.

75.0 mL. The liquid solvent has a mass of 32.5 g

32.5 g and a density of 0.865 g/mL.

0.865 g/mL. Determine the mass of the solid given its density is 1.75 g/mL.

A sample of vinaigrette salad dressing has a total mass of 188 g

188 g , a total volume of 196 cm

3

196⁢ cm3 , and consists only of oil (density=0.882 g/cm

3

)

(density=0.882⁢ g/cm3) and vinegar (density=1.056 g/cm

3

)

(density=1.056⁢ g/cm3) .

What is the volume of each component in this mixture? Assume that the volumes are additive.

How many molecules are present in 2 moles of octane

Nitrogen dioxide (NO 2 ) gas forms an equilibrium system with nitric oxide (NO) gas

and oxygen gas. A syringe is used to inject 0.70 moles of nitrogen dioxide into an

empty, sealed 2.0 L container maintained at a temperature of 185°C. When the

system has come to equilibrium, there are 7.8 × 10 −3 moles of oxygen gas present in

the container. Calculate K eq for the decomposition reaction of NO 2 (g).

A small chemical plant aims to synthesise this chemical from two readily available

petrochemicals, ethene and 2-butene.

(a) Identify the class (family) of organic compound to which 2-butyl ethanoate

belongs.

(b) Explain the chemical property of molecules, such as ethene and 2-butene,

which makes them useful as starting materials in the synthesis of a range of

organic chemicals.

(c) Describe the series of reactions which could be followed to synthesise 2-butyl

ethanoate from ethene and 2-butene as the only organic starting compounds. Your

description should:

● identify a series of reactions which could be followed in the synthesis;

● identify the reaction conditions, including any inorganic reagents, needed to optimise

yield and rate of the main reactions identified;

AND

● include a series of relevant balanced chemical equations, using structural formula

for all organic molecules.

● Give the correct IUPAC names for each structure shown in your equations.

A single electron has a charge of 6.0×10⁻¹⁵ Z. Using zeets and a fictitious unit of mass called the wiggle, w, the charge-to-mass ratio of an electron is 9.6×10⁶ Z/w. What is the mass of an electron in wiggles?

A block of metal has a width of 3.2 cm

cm, a length of 17.1 cm

cm, and height of 5.8 cm

cm . Its mass is 1.3 kg

kg . Calculate the density of the metal.

In separate test tubes, prepare 2mL of 0.2 M of the following buffer solutions by mixing volumes of 0.1 M salt and 0.1 M acid/base

Test tube Number

Buffer solution

Salt

Acid/Base

1

Acetate buffer

0.1 M CH₃COOH

0.1 M CH₃COOH

2

Phosphate buffer

0.1 M Na₂HPO₄

0.1 Na₂HPO₄

QUESTION:

The internal pH of a muscle is 6.8. Calculate the [H₂PO₄^-]/[HPO₄^2-] ratio in the cell. The second dissociation constant of phosphoric acid is 6.31x10^-8