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Margarita [4]
3 years ago
13

If you have a 4.0 g of radioactive substance left after 4 half-lives have passed then how much did you have originally?

Chemistry
1 answer:
kirza4 [7]3 years ago
6 0

4.0 +4.0= 8.0

8.0+8.0=16.0

16.0+16.0=32.0

32.0+32.0=64.0

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The diagram below shows a gas sample being measured with an open-end mercury (Hg) manometer. If a barometer reads 730. 1 torr, w
IRISSAK [1]

The pressure of the gas in the flask (in atm) when Δh = 5.89 cm is 1.04 atm

<h3>Data obtained from the question</h3>

The following data were obtained from the question:

  • Atmospheric pressure (Pa) = 730.1 torr = 730.1 mmHg
  • Change in height (Δh) = 5.89 cm
  • Pressure due to Δh (PΔh) = 5.89 cmHg = 5.89 × 10 = 58.9 mmHg
  • Pressure of gas (P) =?

<h3>How to determine the pressure of the gas</h3>

The pressure of the gas can be obtained as illustrated below:

P = Pa + PΔh

P = 730.1 + 58.9

P = 789 mmHg

Divide by 760 to express in atm

P = 789 / 760

P = 1.04 atm

Thus, the pressure of the gas when Δh = 5.89 cm is 1.04 atm

Learn more about pressure:

brainly.com/question/22523697

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Missing part of question:

See attached photo

5 0
1 year ago
Which of these requires accurate coefficients in a reaction?
aksik [14]

Answer:

A: molar ratio

Molar ratios state the proportions of reactants and products that are used and formed in a chemical reaction.

6 0
3 years ago
9. Sodium reacts with water to produce sodium hydroxide and hydrogen gas, as shown below.
saveliy_v [14]

Answer:

B

Explanation:

2Na + 2H2O2==NaOh + H2

184/23=x/18

x=(184×18)/23

x=144g

4 0
3 years ago
Balancing oxidation-reduction reactions <br> Mg+ N2—&gt;Mg3N2
BartSMP [9]

Answer:

{ \sf{3Mg_{(s)} + N_{2(g)} →Mg _{3}N_{2(s)}}}

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
Read 2 more answers
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