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3 years ago

Addition subtraction: 1) 4.60 + 3

Chemistry

2 answers:

Semenov [28]3 years ago

7 0

7.6 is the answer for the question

sveticcg [70]3 years ago

5 0

Answer:

7.6 is the answer

That the answer

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What group of elements generally have the lowest second ionization energy?

ICE Princess25 [194]

By definition, the first ionization energy is the energy required to remove the most loosely held electron from one mole of gaseous atoms to produce 1 mole of gaseous ions each with a charge of 1+.

4 0

3 years ago

Read 2 more answers

"How much NH4Cl, when present in 2.00 liters of 0.200 M ammonia, will give a solution with pH = 8.20? For NH3, Kb = 1.8 x 10-5"

Andru [333]

Answer:

245.66g of NH₄Cl is the mass we need to add to obtain the desire pH

Explanation:

The mixture of NH3/NH4Cl produce a buffer. We can find the pH of a buffer using H-H equation:

pH = pKa + log [A⁻] / [HA]

Where [A⁻] is the molar concentration of the base, NH₃, and [HA] molar concentration of the acid, NH₄⁺. This molar concentration can be taken as the moles of each chemical

First, we need to find pKa of NH₃ using Kb. Then, the moles of NH₃ and finally replace these values in H-H equation to solve moles of NH₄Cl we need to obtain the desire pH.

pKa NH₃/NH₄⁺

pKb = - log Kb

pKb = -log 1.8x10⁻⁵ = 4.74

pKa = 14 - pKb

pKa = 14 - 4.74

pKa = 9.26

Moles NH₃

2.00L ₓ (0.200mol NH₃ / L) = 0.400 moles NH₃

H-H equation:

pH = pKa + log [NH₃] / [NH₄Cl]

8.20 = 9.26 + log [0.400 moles] / [NH₄Cl]

-1.06 = log [0.400 moles] / [NH₄Cl]

0.0087 = [0.400 moles] / [NH₄Cl]

[NH₄Cl] = 0.400 moles / 0.0087

[NH₄Cl] = 4.59 moles of NH₄Cl we need to add to original solution to obtain a pH of 8.20. In grams (Using molar mass NH₄Cl=53.491g/mol):

4.59 moles NH₄Cl ₓ (53.491g / mol) =

<h3>245.66g of NH₄Cl is the mass we need to add to obtain the desire pH</h3>

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4 years ago

Las Vegas, Nevada is in a desert. How does its rapid population growth affect the

Scrat [10]

Answer:

Many areas of the United States experience explosive population growth. The more people that reside someplace, the more demand there is for water there. Often these urban-growth expansions are unplanned and place extraordinary stress on the water supply system, mainly on the groundwater. The stress often depletes groundwater supply, thereby causing wells to dry up. Then water must be brought from somewhere else to support the local population.

Such situations have occurred all over the United States. For example, increased population growth in the southwestern United States has significantly lowered the water table 50 to 200 feet (depending on the area) since the 1940s. Managing urban growth, efforts to reduce water demand, conservation of the resource, and attempts to increase the water supply all address the problem of exceeding water resource limits.

Human activities affect groundwater quality.

Here are some sources and possible solutions to groundwater pollution:

Agriculture—Reduce usage of pesticides and fertilizers.

Landfills—Monitor for leakage and repair linings.

Underground storage tanks—Remove damaged and unused tanks.

Household wastes—Properly dispose of household hazardous waste.

Septic tank leaks—Properly maintain and repair tanks.

Explanation:

This came from the K12 learning course read this and the answer will be there. I underlined the important parts for the answer.

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3 years ago

How do you measure heat in high school chemistry

FrozenT [24]

Answer: Calories

Explanation: One calorie is the amount of energy required to raise one gram of water one degree Celsius

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3 years ago

How’s it possible for liquid to boil at 25 C?

Lera25 [3.4K]

Answer:

Well, not always. It depends on where you're doing the boiling. In fact, water will boil at about 202 degrees in Denver, due to the lower air pressure at such high elevations

Explanation:

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3 years ago