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denis23 [38]
3 years ago
10

What did Stephen hawking do that was important

Chemistry
1 answer:
azamat3 years ago
4 0
Hawking was the first to set out a theory of cosmology explained by a union of the general theory of relativity and quantum mechanics.
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What steps would you take in a lab to prepare 1000 mL of a 2 M NaCl solution
amm1812

Answer:

The answer to your question is below

Explanation:

Data

Volume = 1000 ml

Concentration = 2M

molecule = NaCl

Process

1.- Calculate the number of moles of NaCl

Molarity = moles/Volume

-Solve for volume

moles = Molarity x Volume (liters)

-Substitution

moles = 2 x 1

-Result

moles = 2

2.- Determine the molar mass of NaCl

NaCl = 23 + 35.5 = 58.5 g

3.- Calculate the mass of NaCl to prepare the solution

               58.5 g -----------------  1mol

                   x      -----------------  2 moles

                       x = (2 x 58.5) / 1

                       x = 117g

4.- Weight 117 g of NaCl, place them in a volumetric flask (1 l), and add enough water to prepare the solution.

7 0
4 years ago
Predict the signs of !iH, !).S, and !).G of the system for the following processes at 1 atm: (a) ammonia melts at - 60°C, (b) am
Elza [17]

Answer:

Explanation:

(a) Given,

Normal melting point of ammonia is -77.7 °C

In this process , ammonia melts at - 60°C  

Now , during the process of melting , ammonia in the solid phase changes to liquid phase, and this increases the number of particles , therefore , the sign of entropy would be positive . And since , the process is an endothermic process , hence , the change in enthalphy sign will be positive .

Even , the temperature of the ammonia is more than its normal melting point .

Therefore ,  

TΔS > ΔH

Hence ,

ΔG < 0

Therefore ,  

ΔH = Positive

ΔS = Positive  

ΔG = Negative.

(b)Given,

Normal melting point of ammonia is -77.7 °C

In this process , ammonia melts at -77.7 °C

Now , during the process of melting , ammonia in the solid phase changes to liquid phase, and this increases the number of particles , therefore , the sign of entropy would be positive . And since , the process is neither endothermic process nor exothermic process, hence , the change in enthalphy sign will be neutral / zero .

Hence ,

ΔG < 0

Therefore ,  

ΔH = 0

ΔS = Positive ΔG = Negative.

(c) Given,

Normal melting point of ammonia is -77.7 °C

In this process , ammonia melts at - 100°C  

Now , during the process of melting , ammonia in the solid phase changes to liquid phase, and this increases the number of particles , therefore , the sign of entropy would be positive . And since , the process is an endothermic process , hence , the change in enthalphy sign will be positive .

Even , the temperature of the ammonia is less than its normal melting point .

Hence ,

ΔG > 0

Therefore ,  

ΔH = Positive

ΔS = Positive  

ΔG = Negative.

7 0
4 years ago
If a cell were compared to a school, which part of the school would represent the cell's nucleus?
bazaltina [42]

Answer:

C-The principal because he or she controls all the activity in the school

4 0
3 years ago
4. In pea plants, purple flower color (P) is a dominant allele, while white flower color (p) is recessive allele. If a pea plant
Maslowich

Its phenotype would be purple, because it is the dominant allele.

3 0
3 years ago
Please help ASAP. I'm stuck on this one question. &gt;.&lt;
Elenna [48]

C. A compound !hope this helps!

7 0
4 years ago
Read 2 more answers
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