Can someone show me how to do this ?

A student investigated how much solid was dissolved in sea water.

SashulF [63]

Answer:

weighing balance/analytical balance

Graduated cylinder/buret

Explanation:

The mass of the evaporating basin could be measured using a weighing balance or an analytical balance. Both are classified as weighing scales but the analytical balance can measure the mass of objects up to 4 decimal places, thus, providing better accuracy in measurement than ordinary weighing balance that can only measure up to 2 decimal places.

In order to measure 50 cm3 of the sea water, a graduated cylinder or a buret can be used. Both equipment can measure up to the same decimal places and, thus, have virtually the same accuracy.

3 0

3 years ago

If anyone is good at chemistry do you mind helping? (●'◡'●)

stepladder [879]

• Before the balloon was placed inside the hot water, the pressure was the same inside and outside the balloon. The hot water raised the kinetic energy of the air molecules inside the balloon, expanding the balloon, through thermal expansion.

• (1) the pressure of air inside the balloon increased, (2) the volume of the inside of the balloon increased as well, and (3) the temperature of the balloon increased. Note that pressure and volume are inversely proportional, and pressure and temperature are directly proportional. Therefore as the temperature increases, the pressure inside will increase, causing an increase in the volume. At a certain point though the volume will increase too much as to cause a significant decrease in pressure.

• The air molecules will gain kinetic energy, hence (1) increasing the molecules's speed, and (2) heating the air molecules.

7 0

4 years ago

For the reaction: CH3NH2(aq) + H2O(aq) ⇌ CH3NH3 +(aq) + OH- Determine the change in the pH (ΔpH) for the addition of 6.7 M CH3NH

Korolek [52]

Answer:

The change in the pH (ΔpH) is 2,17

Explanation:

The reaction:

CH₃NH₂(aq) + H₂O(aq) ⇌ CH₃NH₃⁺(aq) + OH⁻

$kb = \frac{[OH^{-}][CH_{3}NH_{3}^+]}{[CH_{3}NH_{2}]}$ (1)

In equilibrium, a solution of CH₃NH₂ 4,7M produces:

[CH₃NH₂] = 4,7 - x

[CH₃NH₃⁺] = x

[OH⁻] = x

Replacing in (1):

$4,38x10^{-4} = \frac{x^2}{4,7-x}$

x² + 4,38x10⁻⁴x - 2,0586x10⁻³ = 0

The solutions are:

x = -0,0456 No physical sense. There are not negative concentrations.

x = 0,04515 Real answer.

The concentration of [OH⁻] is 0,04515 M.

As pOH = -log [OH⁻] And pH+pOH = 14. The pH of this solution is:

pH = 12,65

The addition of 6,7M produce this changes in concentrations:

[CH₃NH₂] = 4,656 + x

[CH₃NH₃⁺] = 6,74515 - x

[OH⁻] = 0,04515 - x

Replacing in (1) you will obtain:

x² - 6,7907x + 0,3025 = 0

Solving for x:

x = 6,74586 No physical sense

x = 0,04484 Real answer.

Thus, [OH⁻] = 0,04515 - 0,044842 = 3,08x10⁻⁴M

pOH = 3,51.

pH = 10,49

Thus ΔpH is 12,65 - 10,49 = 2,16 ≈ 2,17

I hope it helps!

4 0

4 years ago

The second electron shell of an atom can hold a maximum of ______ electron(s).

lawyer [7]

Can hold max of 8 electrons

5 0

3 years ago

You have identified a substance to be solid in nature. which characteristics will justify your identification?

weeeeeb [17]

This question includes four answer choices: A. definite volume, highest molecular motion, highest kinetic energy B. indefinite volume, least molecular motion, highest kinetic energy C. definite volume, least molecular motion, lowest kinetic energy D. definite volume, no molecular motion, lowest kinetic energy Solids do not have the highest molecular motion (on the contrary they have the least molecular motion), so you can discard option A. Solids have a definite volume and the highest kinetic energy (given that they have the least molecular motion), so you discard option C. Molecules always have a vibrational motion, so you discard option D. Option C, have only characteristics that correctly describes a solid: definite volume, least molecular motion, lowest kinetic energy. Therefore, the answer is the option C.

4 0

3 years ago

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