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Ratling [72]
3 years ago
9

Can someone help me with questions 4-5 21 points

Chemistry
1 answer:
sp2606 [1]3 years ago
8 0

4. describe three ways carbon dioxide was removed from the Earth's atmosphere.

Answer: Forests: Photosynthisis helps clear carbon dioxide naturally, Soils naturally store carbon, but agricultural soils are running a big deficit due to intensive use. Because agricultural land is so expansive, Bio-energy with Carbon Capture and Storage (BECCS) is another way to use photosynthesis to combat climate change. However, it is far more complicated than planting trees or managing soils — and it doesn’t always work for the climate.

5. Explain why there is now 21% Oxygen in the Earth's atomosphere compaired to little or no Oxygen in the Earth's atmosphere 4.5 billion years ago.

Answer: cientists believe that the Earth was formed about 4.5 billion years ago. Its early atmosphere was probably formed from the gases given out by volcanoes. It is believed that there was intense volcanic activity for the first billion years of the Earth's existence.The early atmosphere was probably mostly carbon dioxide, with little or no oxygen. There were smaller proportions of water vapour, ammonia and methane. As the Earth cooled down, most of the water vapour condensed and formed the oceans.

Sorry its soooo long TwT

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Help me with this please
Pavel [41]
I believe it’s D because they are the largest decimals
8 0
3 years ago
If 12.5 grams of strontium hydroxide is reacted with 150 mL of 3.5 M carbonic acid, identify the limiting reactant.
kiruha [24]

Answer:

Sr(OH)₂ will be the limiting reagent.

Explanation:

First of all, you should know the following balanced chemical equation:

2 H₂CO₃ + 2 Sr(OH)₂ → 4 H₂O + Sr₂(CO₃)₂

The balanced equation is based on the Law of Conservation of Mass, which says that matter cannot be created or destroyed. Therefore, the number of each type of atom on each side of a chemical equation must be the same.      

The limiting reagent is one that is consumed first in its entirety, determining the amount of product in the reaction. When the limiting reagent is finished, the chemical reaction will stop.

To determine the limiting reagent, it is possible to use the reaction stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction). By stoichiometry the following amounts in moles react:

  • strontium hydroxide: 2 moles
  • carbonic acid: 2 moles

Now, you know the following masses of the elements:

  • Sr: 87.62 g/mole
  • O: 16 g/mole
  • H: 1 g/mole

So the molar mass of strontium hydroxide is:

Sr(OH)₂= 87.62 g/mole + 2*(16 g/mole + 1 g/mole)= 121.62 g/mole

You apply the following rule of three, if 121.62 grams of hydroxide are present in 1 mole, 12.5 grams in how many moles are they?

moles of strontium hydroxide=\frac{12.5 grams*1 mole}{121.62 grams}

moles of hydroxide= 0.103 moles

On the other hand, you have 150 ml of 3.5 M carbonic acid. Since molarity is the concentration of a solution expressed in the number of moles dissolved per liter of solution, you can apply the following rule of three: if in 1 L there are 3.5 moles of carbonic acid, in 0.150 L (being 1 L = 1000 mL, 0.150 L = 150 mL) how many moles of acid are there?

molesofcarbonicacid=\frac{0.150 L*3.5 moles}{1 L}

moles of carbonic acid= 0.525 moles

Finally, to calculate the limiting reagent, you can use a simple rule of three as follows: if by stoichiometry 2 mole of strontium hydroxide reacts with , how much moles of carbonic acid will be needed if 0.103 moles of strontium hydroxide react?

molesofcarbonicacid=\frac{0.103 moles of strontium hydroxide*2 moles of carbonic acid}{2 moles of strontium hydroxide}

moles of carbonic acid= 0.103 moles

But 0.525 moles are available. Since more moles are available than you need to react with 0.103 moles of strontium hydroxide, <u><em>Sr(OH)₂ will be the limiting reagent.</em></u>

7 0
3 years ago
At one time in the Earth’s history, many people thought the world was flat. Which best explains why the model of the Earth is no
GenaCL600 [577]

Answer:

<u>Models are limited by science - the more that was discovered, the better the model could be made.</u>

Explanation:

Models in science are meant to represent things in science. Since science controls the reliability of a model, when science changes, so does the model. Otherwise the model would be pseudoscientific.

5 0
3 years ago
The molar mass of sucrose (C12H22O11) is 342.3 g/mol. A chemist has a 0.500-mol sample of sucrose. What is the mass, in grams, o
Gekata [30.6K]
171 is the answer that I got after my calculations.
8 0
3 years ago
Read 2 more answers
Which is a correct comparison between the modern quantum model and John Dalton’s model of the atom?
REY [17]

Answer:

Explanation:

The modern model recognizes particles in the atom, whereas Dalton's model does not.

7 0
3 years ago
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