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3 years ago

When patterns of stars appear to move across the sky, it provides evidence that ________.

Chemistry

1 answer:

Alexus [3.1K]3 years ago

6 0

Answer:

Answered B

Explanation:

The earth moves which makes the stars and everything in space seem like its moving

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What causes the changes in air pressure on the earth surface

Fudgin [204]

<span>Atmospheric Pressure</span>

5 0

3 years ago

Aspirin can be prepared from salicylic acid ( C 7 H 6 O 3 CX7HX6OX3), which has a molar mass of 138.12 g/mol, and acetic anhydri

pychu [463]

Answer: The theoretical yield of aspirin is 4.14 g

Explanation:

To calculate the moles :

$\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}$ $\text{Moles of salicylic acid}=\frac{3.20g}{138.12g/mol}=0.023moles$

mass of acetic anhydride = $density\times volume =1.082g/ml\times 3.71ml=4.01g$

$\text{Moles of acetic anhydride}=\frac{4.01g}{102.04g/mol}=0.039moles$

$C_9H_6O_3+C_4H_6O_3\rightarrow C_9H_8O_4+C_2H_3O_2$

According to stoichiometry :

1 mole of salycylic acid require 1 mole of acetic anhydride

Thus 0.023 moles of salycylic acid require= $\frac{1}{1}\times 0.023=0.023moles$ of acetic anhydride

Thus salycylic acid is the limiting reagent as it limits the formation of product and acetic anhydride is the excess reagent.

As 1 mole of salycylic give = 1 mole of aspirin

Thus 0.023 moles of salycylic acid give = $\frac{1}{1}\times 0.023=0.023moles$ of aspirin

Mass of aspirin = $moles\times {\text {Molar mass}}=0.023moles\times 180.15g/mol=4.14g$

Thus theoretical yield of aspirin is 4.14 g

4 0

3 years ago

I need some help with chemistry. Let me know if you are good at it!

tekilochka [14]

Answer:

I think im good at it i have an A in the class

Explanation:

lol

3 0

3 years ago

Identify whether each reaction represents a chemical reaction or a nuclear reaction by filling in the blank with the word ‘chemi

valkas [14]

A chemical reaction is defined as the reaction between two or more substances that produces new substances/compounds.

On the other hand, a nuclear reaction is a reaction that alters the nucleus of a certain atom. This can be done either by splitting the nucleus or by joining this nucleus with another one.

Reaction 1:
Cl₂ + H₂ ............> 2 HCl
This is the combination of two elements to produce a new compound.
Therefore, this reaction is a chemical reaction

Reaction 2:
²₁H + ³₁H .........> ⁴₂H + ¹₀n
This is an alteration in the nucleus of a hydrogen atom by bonding it with another nucleus.
Therefore, this reaction is a nuclear reaction

Hope this helps :)

5 0

3 years ago

Read 2 more answers

Could the cuttlefish tell the difference between the blue and yellow in the lab?

jeka94

Answer:

<em>yes</em>

Explanation:

the cuttle fish tell the difference between blue and yellow

5 0

1 year ago