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BlackZzzverrR [31]
3 years ago
15

In a __________________ reaction, elements are not changed, just rearranged. Small amounts of energy take place.

Chemistry
2 answers:
vitfil [10]3 years ago
8 0
D. Chemical.
In a chemical reaction, elements are not changed, just rearranged. Small amounts of energy take place.
emmainna [20.7K]3 years ago
3 0
D. In a Chemical reaction, elements are not changed, just rearranged. Small amounts of energy take place.
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Part 1: Cats falling out of windows
timurjin [86]

Answer:

A cat that falls out of the window even if it seems to be doing well, must urgently go to a veterinary clinic in order to be placed under surveillance for at least 24 to 72 hours

Explanation:

3 0
3 years ago
How many moles of helium are 8.84×10^24 atoms of He?
viva [34]

Answer:

14.77 mol.

Explanation:

  • It is known that every 1.0 mole of compound or element contains Avogadro's number (6.022 x 10²³) of molecules or atoms.

<u><em>Using cross multiplication:</em></u>

1.0 mole of He contains → 6.022 x 10²³ atoms.

??? mole of He contains → 8.84 x 10²⁴ atoms.

<em>∴ The no. of moles of He contains (8.84 x 10²⁴ atoms) </em>= (1.0 mol)(8.84 x 10²⁴ atoms)/(6.022 x 10²³ atoms) =<em> 14.77 mol.</em>

8 0
3 years ago
How much energy is evolved during the formation of 197 g of Fe, according to the reaction below?
hoa [83]

Answer:

ΔH for formation of 197g Fe⁰ = 1.503 x 10³ Kj => Answer choice 'B'

Explanation:

Given Fe₂O₃(s) + 2Al⁰(s) => Al₂O₃(s) + 2Fe⁰(s) + 852Kj

197g Fe⁰ = (197g/55.85g/mol) = 3.527 mol Fe⁰(s)

From balanced standard equation 2 moles Fe⁰(s) => 852Kj, then ...

3.527 mole yield (a higher mole value) => (3.527/2) x 852Kj = 1,503Kj (a higher enthalpy value).

______

NOTE => If 2 moles Fe gives 852Kj (exo) as specified in equation, then a <u>higher energy value</u> would result if the moles of Fe⁰(s) is <u>higher than 2 moles</u>. The ratio of 3.638/2 will increase the listed equation heat value to a larger number because 197g Fe⁰(s) contains more than 2 moles of Fe⁰(s) => 3.527 mole Fe(s) in 197g.  Had the problem asked for the heat loss from <u>less than two moles Fe⁰(s)</u> - say 100g Fe⁰(s) (=1.79mole Fe⁰(s)) - then one would use the fractional ratio (1.79/2) to reduce the enthalpy value less than 852Kj.  

8 0
3 years ago
Describe the difference between accuracy and precision. How do these two concepts relate to the idea of significant digits?
Soloha48 [4]

Answer:

Accuracy of a measured value refers to how close a measurement is to the correct value. The uncertainty in a measurement is an estimate of the amount by which the measurement result may differ from this value. Precision of measured values refers to how close the agreement is between repeated measurements.

Explanation:

3 0
2 years ago
What element has 8 valence electrons
Maksim231197 [3]
An element with 8 valence electrons is Neon (Ne).
Ps: Any element under group 18 has 8 valence electrons except for Helium (He).
4 0
3 years ago
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