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____ [38]
3 years ago
9

if a 2.0g sample of water at 5.0celcius absorbs 21.8Joules of energy, the temprature of the sample will be raised by

Chemistry
1 answer:
Cerrena [4.2K]3 years ago
8 0
You'd use the temperature change equation. The specific heat of water is always 4.18J/(g °C).
Equation to use: q=mCΔT

21.8=(2.0)(4.18)(Tf-5)
21.8=(8.36)(Tf-5)
21.8/8.36=Tf-5
2.61=Tf-5
2.61+5=Tf
Tf=7.61 °C

Since you want to know how many °C it raises, you wouldn't pay attention to the last 2 steps, however if you need to know the final temp, you want to go to the last step.
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Why do reactivity increases on moving from top to bottom in group 2 of modern periodic table?
Nikolay [14]

Answer:

that's because....

group 1 (e.g Na, K) those tend to lose one electron to gain noble gas electron configuration.

they can achieve that by just losing one electron from their outer shell.

as you go down the group 1, element gets bigger in size, which means there is more space between nucleus (which is in center of atom) and electron of outer shell. the more far away they are the less attraction force between them.

so its easier for potassuim to lose one electron than for lithuim.

so that means potassium will easily give up 1 electron to react with non metal or other element therefore it is more reactive than lithuim

but in case of non metal, the opposite happens but simple to understand.

as you go down the group 7 (halogen- Cl, Br, I) element will get bigger therefore force between nucleus and outer electron is getting smaller. they have to gain 1 electron in order to fill the outer shell (to gain noble gas electron configuration.)

as florine is more smaller in size than clorine it is more reactive because florine has more tendency to pull extra electron from metal or other element towards its side. so it easily gain 1 electron to react.

3 0
3 years ago
rank the four gases (air, exhaled air, gas produced from the decomposition of H2O2, gas from decomposition of NaHCO3, in order o
SVEN [57.7K]

Answer: H₂O₂ (94%) > Air (23%) > Exhaled air (13%) > NaHCO₃ (0%)


Initial important note:


Although NaHCO₃ contents oxygen atoms, and you can calculate its compositoin, the resulting gas does not containg pure oxygen gas (O₂). For the comparisson it is not useful to calculate the content of oxygent atoms, but the concentration of O₂ gas. As such, the gas from NaHCO₃ contains 0% of pure O₂, that is why it is ranked last.


1) Air:


Source: internet


Approximate 23%. It is variable, because air is not a pure substance but a mixture of gases, whose compositon is not unique.


2) Exhaled air:


Source: internet.


Approximate 13%. The compositon of the air changes in our lungs, due to the respiration process: we inhale fresh air with around 23% of oxygen, part of this oxygen pass to the cells (lungs - blood - heart - cells) and then it is exhaled with a lower content of air and a greater content of CO₂


3) Air from the decomposition of H₂O₂.


In this case we can do a chemical calculation, since we can state the chemical equation of the reaction:


i) Chemical Equation:


H₂O₂ (g) → H₂ (g) + O₂ (g)


ii) mole ratio of the products 1 mol H₂ : 1 mol O₂


iii) convert moles into mass (grams)


1 mol H₂ × 2 × 1.008 g/mol = 2.016 g


1 mol O₂ × 2 × 15.999 g/mol = 31.998 g


Composition, % = [31.998 g / (2.016 g + 31.998 g) ] × 100 ≈ 94%



4) Air from the decomposition of NaHCO₃:


i) chemical equation:


2 NaHCO₃(s) → Na₂CO₃(s) + CO₂(g) + H₂O(g)


ii) mole ratio: take into account only the gases in the products:


1 mol CO₂ (g) : 1 mol H₂O


iii) mass in grams


CO₂: molar mass ia approximately 44.01 g/mol


H₂O: molar mass is approximately 18.02 g/mol


iii) Those gases although have oxygen atoms, do not hae free oxygen gas, which is what we are compariing. That means, that from the decomposition of NaHCO₃ you get 0% oxygen gas.


5) The result is:


H₂O₂ (94%) > Air (23%) > Exhaled air (13%) > NaHCO₃ (0%)

7 0
3 years ago
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A whale has a calf and a bacteria replicates through cloning. Both of these are examples of_______ . worth 20 points
sergij07 [2.7K]

Answer:

growth and development

Explanation:

I did the test

4 0
2 years ago
Read 2 more answers
Synthesis of cholesterol takes place in the
aliina [53]
The small intestine i think :) hope that helps
7 0
2 years ago
What are the coefficients of the balanced reaction? _CH4 + _CI2 ➡ _CCI4 + _HCI​
stealth61 [152]

Answer:

CH4 + 4Cl2 --> CCl4 + 4HCl

Explanation: Message me if you need a thorough explanation

7 0
2 years ago
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