Answer:
- <em><u>A physical change has occurred, with no energy change.</u></em>
Explanation:
When a pencil lead is broken there is not change of any chemical properties, therefore it is not a chemical change, but just a physical change. In this case the change is just the number of pieces and dimensions.
Chemical changes always involve the formation of new different substances; the bonds between the atoms of the starting substances (reactants) breake and new bonds are formed leading to new substances (products) with different chemical composition (arrange of atoms). Chemical changes occur through chemical reactions.
Hence, if there is not change on the chemical composition, you think on physical changes. Physical changes include change in shape, size, state of matter (e.g. solid, liquid, gas). In the case of a pencil lead breaking, it is a change in shape and size.
Also, since energy has not been absorbed or released during the change, the energy of the pencil lead before having been broken is equal to the sum of the energies of the pieces of pencil lead obtained. So, this is a physical change with no energy changes.
Some examples of physical changes that include change in energy are the change of state (e.g. solid to liquid or liquid to gas) and the dissolution of a compound.
First of all, we convert the amount of item given in moles into grams. Each mol of steam is 18 grams of steam. Such that the heat released during the evolution of per gram of steam is,
H = (2.01 J/goC)(160 - 100) + 2260 J/g + (4.179 J/gC)(100 - 0) + (333.5 J/g) + (2.09 J/gC)(45oC)
H = 3226.05 J/g
Then, we multiply this value by 18 g to get the final answer which is equal to 58068.9 Joules.
Answer:
5 will come in blank
4KMnO₄ ----------> 2K₂O + 4MnO + 5O₂
Explanation:
Reaction:
4KMnO₄ ----------> 2K₂O + 4MnO + ____O₂
this reaction is the dissociation reaction in which KMnO₄ is break down into its component.
KMnO₄ upon dissociation gives Potassium oxide, manganese oxide and liberate oxygen
Balance Chemical Equation:
A balanced chemical equation is that in which the the number of the reactant atoms equal to the number of the product atom.
For example if the oxygen at the reactant side is 4, the number of oxygen should be 4 on the product side.
So for this purpose we have to balnce the reaction and number of atoms on each side of the arrow
if we see the given Equation
Numbers of atom on reactant Side:
K = 4
Mn = 4
O = 16
Numbers of atom on reactant Side:
K = 4
Mn = 4
O = 6 instead of blank oxygen molecule
so from the above data we have 10 oxygen less.
If we put the 5 in the blank then we will have 10 oxygen and equation will be balanced
So the balanced Equation will be
4KMnO₄ ----------> 2K₂O + 4MnO + 5O₂
That is true because a hypothesis is like a conclusion, a thinking of what could happen
Answer:
Explanation:
The atomic number tells you how many protons are in an element. Each element has a different number of protons, so a specific number of protons will also help you easily identify that particular element. For example, if you are given that an element has an atomic number of 1, you would know the element is hydrogen because other elements have different amounts of protons and thus different atomic numbers.
