A student is given a sample of a blue copper sulfate hydrate. He weighs the sample in a dry covered porcelain crucible and got a

Response:

The pKa value is 13.0.

Clarification:

pKa + pKb = 14

For trimethylamine, Kb = 6.3 ×

Calculating pKb: pKb = - log (6.3 × )

= 1.0

Thus, pKa = 14 - pKb = 14 - 1.0

pKa = 13.0

Verification: The typical range for pKa in weak acids is from 2 to 13.

Solution:

Washing Clothes & Dissolving Sugar

Clarification:

Consider each scenario:

1) For washing clothes, water is essential; without it, washing is ineffective.

2) Connecting brake pedals to brake pads requires solids, not liquids.

3) To deodorize a space, one would likely reach for an aerosol spray, which is a gas.

4) Sculpting involves solid tools and a solid medium.

5) Dissolving sugar necessitates a liquid to be effective!

6) While one might assert that paint is a liquid, it still might not fit the category; I would categorize this application as solid.

7) Gears employed in machinery are solid components!

Clarification:

To obtain the specific element, you should multiply the grams provided by the ratio of grams of that particular element within its complete compound.

Since the query did not indicate the amount of NO2 produced, we can consider its mass to be negligible, thus assigning 1 mole to Nitrogen.

After four hours of cooling, the soup reached a temperature of 140 F (or) 42 C.

Explanation:

A food worker allowed a cup of soup to cool for two hours,

step 1: The temperature attained in two hours is 70 F (or) 21 C

step 2: Consequently, in four hours, this doubles the value

Therefore, the temperature after four hours is 2(70)= 140 F (or) 2(21)= 42 C