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3 years ago

How old are the oldest fossils on earth?

Chemistry

2 answers:

blondinia [14]3 years ago

5 0

the oldest fossils on earth are 3.5 billion years

sertanlavr [38]3 years ago

4 0

Over 3.5 billion years old! Hope this helps :)

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Olympic runners wear spandex clothing to counteract the same force that also affects airplanes in flight. What force is it?

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Explanation: A p e x

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3 years ago

What is the answer to number 6

faltersainse [42]

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4 years ago

Explain how using dimensional analysis could have prevented this crash

emmainna [20.7K]

Dimensional analysis is a convenient technique to determine if the solution you're following would lead you to the answer that you're looking for. It is the manipulation of units. Like units are cancelled whenever they appear on the numerator and the denominator side. For example, if the speed is 5 m/s and the time is 2 s, the distance would be:

(m/s)*(s) = m

So, you would know that the solution would be 5*2 because it yields the unit for distance.

Hence, dimensional analysis could prevent crash by calculating the right velocities or distances of the two vessels to prevent collision.

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4 years ago

Stable isotopes usually have a ____ number of protons and a ____ number of neutrons

Yuliya22 [10]

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For example: Carbon always has 6 protons
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3 0

3 years ago

How many grams of LiOH are produced from 9.89 g of Li?

Nonamiya [84]

Taking into account the stoichiometry of the reaction, 34.12 grams of LiOH are produced from 9.89 g of Li.

In first place, the balanced reaction is:

2 Li + 2 H₂O ⇒ 2 LiOH + H₂

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

Li= 2 moles
H₂O= 2 moles
LiOH= 2 moles
H₂= 1 mole

The molar mass of each compound is:

Li= 6.94 g/mole
H₂O= 18 g/mole
LiOH= 23.94 g/mole
H₂= 2 g/mole

By reaction stoichiometry, the following amounts of mass of each compound participate in the reaction:

Li= 2 moles× 6.94 g/mole= 13.88 g
H₂O= 2 moles× 18 g/mole= 36 g
LiOH= 2 moles× 23.94 g/mole= 47.88 g
H₂= 1 mole× 2 g/mole= 2 g

Then you can apply the following rule of three: if by reaction stoichiometry 13.88 g of Li produce 47.88 g of LiOH, 9.89 g of Li produce how much mass of LiOH?

$mass of LiOH=\frac{9.89 g of Li*47.88 g of LiOH}{13.88 f of Li}$

Solving:

<u><em>mass of LiOH= 34.12 grams</em></u>

Finalli, 34.12 grams of LiOH are produced from 9.89 g of Li.

Learn more:

7 0

3 years ago