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ch4aika [34]
2 years ago
9

When some water condensed

Chemistry
1 answer:
Olin [163]2 years ago
7 0

Answer:

38.43 J

Explanation:

9.15 * 4.2 = 38.43 J

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A sample of TNT, C7H5N3O6 , has 8.94 × 1021 nitrogen atoms. How many hydrogen atoms are there in this sample of TNT?
Bess [88]

Answer:

1.49×10²² atoms of H are contained in the sample

Explanation:

TNT → C₇H₅N₃O₆

1 mol of this has 7 moles of C, 5 moles of H, 3 moles of N and 6 moles of O

Let's determine the mass of TNT.

Molar mass is = 227 g/mol

As 1 mol has (6.02×10²³) NA atoms, how many moles are 8.94×10²¹ atoms.

8.94×10²¹ atoms / NA = 0.0148 moles

So this would be the rule of three to determine the mass of TNT

3 moles of N are in 227 g of compound

0.0148 moles of N are contained in (0.0148 .227) / 3 = 1.12 g

Now we can work with the hydrogen.

227 grams of TNT contain 5 moles of H

1.12 grams of TNT would contain (1.12 .5) / 227 = 0.0247 moles

Finally let's convert this moles to atoms:

0.0247 mol . 6.02×10²³ atoms / 1 mol = 1.49×10²² atoms

8 0
3 years ago
A scientist digs up sample of arctic ice that is 458,000 years old. He takes it to his lab and finds that it contains 1.675 gram
Fiesta28 [93]

Answer:

6.70 grams of krypton-81 was present when the ice first formed

Explanation:

Let use the below formula to find the amount of sample

N= N_0(\frac{1}{2})^n

where

n = \frac{t}{t_{\frac{1}{2}}}

here

t =  458,000 years

t_{\frac{1}{2}} = 229,000

\frac{t}{t_{\frac{1}{2}}} = \\frac{ 458,000}{229,000}

n = \frac{t}{t_{\frac{1}{2}}} = 2.000

Now substituting the values

1.675 = N_0(\frac{1}{2})^{2.000}}

1.675 = N_0\times (0.2500)

N_0= \frac{1.675}{0.2500}

N_0=6.70

3 0
3 years ago
Which organism is the carnivore in this food web?
mihalych1998 [28]
Among the choices, the only one that can be considered a carnivore is C. Adelie penguin. Adelie penguins are found in the Arctic, and feed on aquatic creatures such as krill, fish, and squid. Krill is a type of crustacean that feeds on phytoplankton, which is at the bottom of the food chain.
8 0
3 years ago
A (n) blank is a movement or trembling of the ground that is caused by a sudden release of energy when rocks move along a fault.
GuDViN [60]
An earthquake is your answer.
3 0
3 years ago
What is the mass of 4 moles of helium, He?
aniked [119]
I am pretty sure it is 4.002602
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