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svet-max [94.6K]
3 years ago
7

Could someone please help me? You can ignore number 3:)

Chemistry
1 answer:
il63 [147K]3 years ago
6 0

Answer:

Question 2: Because the elements could be unstable, forming elemental compounds.

Question 1: Water is made up of Hydrogen and oxygen, which is namely called H2^o What makes it a pure substance is the little mass and molecules it's made up of.

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What is the enthalpy of reaction for the decomposition of calcium carbonate?
77julia77 [94]

Answer:

First Blank: 656.3 kJ

Second Blank: Endothermic

Explanation:

Edge 21'

4 0
3 years ago
2. A balloon full of air has a volume of 2.75 L at a temperature of 18°C. What is the balloon's volume
Sphinxa [80]

Answer:

3.01 L

Explanation:

V

1

: 2.75L

T

1

:  

18

∘

C

V

2

: ?

T

2

:  

45

∘

C

If you know your gas laws, you have to utilize a certain gas law called Charles' Law:

V

1

T

1

=

V

2

T

2

V

1

is the initial volume,  

T

1

is initial temperature,  

V

2

is final volume,  

T

2

is final temperature.

Remember to convert Celsius values to Kelvin whenever you are dealing with gas problems. This can be done by adding 273 to whatever value in Celsius you have.

Normally in these types of problems (gas law problems), you are given all the variables but one to solve. In this case, the full setup would look like this:

2.75

291

=

V

2

318

By cross multiplying, we have...

291

V

2

= 874.5

Dividing both sides by 291 to isolate  

V

2

, we get...

V

2

= 3.005...

In my school, we learnt that we use the Kelvin value in temperature to count significant figures, so in this case, the answer should have 3 sigfigs.

Therefore,  

V

2

= 3.01 L

5 0
4 years ago
An attempt to explain observations of the natural world is
atroni [7]
A pseudoscientific theory
3 0
3 years ago
The reaction gives off heat energy, so it is an __________ reaction
Alex_Xolod [135]
Since the reaction gives off heat energy it is considered to be an exothermic reaction
3 0
3 years ago
Calculate the energy of a photon of light with<br> a frequency of 5.109 × 1016 Hz.
lyudmila [28]

Answer:

The energy of the photon is 1.718×10−26J.

Explanation:

The energy of the photon is

1.718 × 10 − 26J. You use the formula  E =\frac{hc}{λ}, where h is Planck's Constant,c is the speed of light, and λ is the wavelength of the photon.

E=\frac{hc}{λ}=\frac{6.626×10−34J⋅ s×2.998×108m⋅s-1}{11.56m} = 1.718×10−26J.

4 0
3 years ago
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