Answer: b: takes place when atoms become inactive
Explanation: the model described above is a nuclear fission reaction, a reasonably controlled reaction that releases energy and is employed in nuclear power plants. In these reactions one Atom is split into two lighter ones and there's a resultant release of energy in the process. The original Atom becomes depleted (inactive) as is the case with Uranium 235.
This reaction is opposed to fusion reactions that occur in nature e.g. the sun, and are basically uncontrollable — involving the combination of two atoms into one.
at 100 degrees Celsius. Calculate the amount of heat required for this
conversion.
3. A student measured 15.0 grams of ice in a beaker. The beaker was then
placed on a hot plate where it was heated uniformly for a certain amount
of time. During the melting process of the ice, the student noted that the
temperature was at 0 degree Celsius. When all the ice converted to water,
the final temperature was also at 0 degree Celsius. How much heat was
used to melt the ice?
4. If 5.0 grams of water was cooled from 50 degrees Celsius to 40
degrees Celsius, then calculate the amount of heat released by the water.
5. A certain amount of water used exactly 84.0 Joules of heat energy to
change from 25.0 degrees Celsius to 35 degrees Celsius. How many
grams of water was used?
Please help me
Answer:
Explanation:
1 )
amount of heat required = mass x specific heat x rise in temperature
= 25 x 4.2 x 20 = 2100 J .
2 )
Amount of heat required
= mass x latent heat of vaporisation
= 50 x 2260 = 113000 J .
3 )
Amount of heat required in melting the ice
= mass x latent heat of fusion
= 15 x 336 = 5040 J
4)
heat released in cooling water
= mass x specific heat x fall in temperature
= 5 x 4.2 x 10
= 210 J
5 )
amount of heat required = mass x specific heat x rise in temperature
84 = mass x 4.2 x 10
mass = 2 grams .
Find the abundance of each isotope.
Let y/100 = the abundance of copper-10
and (100 - y)/100 = the abundance of copper-11
10.2 = (y/100 x 10) + [(100 - y)/100 x 11]
10.2 = 10y/100 + 1100/100 - 11y/100
1020 = 10y + 1100 - 11y
-80 = -y
y = 80
Abundance of boron-10 = 10/100 = 10%
Abundance of boron-11 = 100 - 10 = 90%
When the formation of a substance is negative, it means that it releases heat to the surroundings. When it releases heat to the surroundings, the reaction is exothermic. When it absorbs heat from the surroundings, the reaction is endothermic.
For example,
"Which of the following molecules is expected to have one or more unpaired electrons? Check all that apply.
O2-
F2+
N22-
O22-"
Any help would be appreciated. ...?
To determine unpaired electrons, look at the valence electrons in an ion's molecule, accounting for extra or absent electrons due to the ion's charge. For instance, O2- and F2+ have one unpaired electron, but N22- is not a valid ion, and O22- electrons are all paired.
To determine if a molecular ion will have one or more unpaired electrons, we need to look at the number of valence electrons in the molecule and take into account any extra or absent electrons due to the charge of the ion.
For example, O2- has 12 + 1 = 13 valence electrons (6 from each oxygen atom and 1 extra due to the negative charge). It requires 14 for all the electrons to be paired (2 in each oxygen's inner shell and 4 bonds or lone pairs in the outer shell), thus there is one unpaired electron in O2-.
However, in F2+, there are only 13 electrons because one electron is lost due to the positive charge. Like oxygen, fluorine also prefers to have 7 electrons in its outer shell, so there are also unpaired electrons in F2+.
N22- doesn’t exist because nitrogen normally forms triple bond and doesn’t need or want to take extra electrons, so this molecular ion is not valid.
O22- has 14 + 2 = 16 valence electrons and this total number of valence electrons is an even number, which indicates all the electrons are paired.
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What are the reactions and what do I need to calculate?