Answer:
The internal energy(ΔE) of a substance is calculated below:
From the first law of thermodynamics;
ΔE=q+w
Explanation:
<u>ΔE=q+w</u>
here;
+q=endothermic reaction
-q=exothermic reaction
+w=work done on the system
-w=work done by the system
Given:
q=+1.62kJ=1620J
w=-874J
To solve:
the internal energy(ΔE)
We know:
ΔE=q+w
<em>according to the problem;</em>
ΔE=q-w
since;
w=-874J (i.e.)work is done by the system.
ΔE=1620-874
ΔE=+746J
Therefore the internal energy is +746J
i.e. the option is "c"(+746J)
Answer:
93%
Explanation:
First write the balanced reaction
C3H8 + 5O2 --> 3CO2 +4H2O
2nd, find the theoretical yield
2L C3H8 (1mol/22.4L) (3 mol CO2/1 molC3H8) (22.4 L/ 1mol) = 6L
3rd, Find percent yield
%yield = (actual / theoretical) x100 = (5.7/6) x 100 = 93%
Answer:
Explanation:
The<em> half-life </em>time of a radiactive isotope (radioisotope) is a constant value, meaning that the amount of the radioisotope that decays will be (1/2) raised to the number of half-lives passed.
Naming A₀ the initial amount to the radioisotope, you can build this table to find the amount left.
Number of half-lives amount of radiosotope left
0 A₀
1 (1/2) × A₀
2 (1/2)×(1/2)×A₀ = (1/2)² × A₀
3 (1/2)³ ×A ₀
4 (1/2)⁴ × A₀
n (1/2)ⁿ × A₀
Now calculate the number of half-lives the strontium-90 sample has passed after 100 years:
- n = 100 years / 28.1 years ≈ 3.5587
Hence, the amount of strontium-90 is:
In percent, that is:
Rounding to two significant figures, that is 8.5%.
<u>Conclusion</u>: <em>The percent of strontium-90 left after 100 yeaers is 8.5% </em>(choice number 4).
Serotonin is a molecule composed of 10 carbon atoms (black), 12 hydrogen atoms (white), 2 nitrogen atoms (blue), and 1 oxygen atom (red).
30-60 breaths per minute
A rabbit's heart rate should be 120-150 beats per minute. A rabbit's respiration rate should be 30-60 breaths per minute. A rabbit's temperature should be 101.3-104F.
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