Answer:
The correct answer is MgCO₃.5H₂O.
Explanation:
Based on the given information,
The mass of hydrate of magnesium carbonate given is 15.67 grams, and the mass of anhydrous magnesium carbonate given is 7.58 grams.
Now the mass of water will be,
= 15.67 grams – 7.58 grams
= 8.09 grams
The molecular mass of magnesium carbonate is 84.32 grams, the moles of MgCO₃ can be determined by using the formula,
Number of moles = Mass/Molecular mass
Moles of MgCO₃ = 7.58/84.32
= 0.0898 moles
Similarly, the number of moles of water will be,
Moles of H₂O = 8.099/18.02
= 0.4489 moles
After getting the values, there is a need to choose the smaller value and use it to divide both the values to get the ratio,
MgCO₃ = 0.0898/0.0898 = 1
H₂O = 0.4489/0.0898 = 4.9 or 5
Thus, the molecular formula for the hydrate will be MgCO₃.5H₂O.
Answer:
The answer to your question is: A.
Explanation:
A. C + 2H₂ ⇒ CH₄ This is the right answer because the equation is balanced and is according to the law of conservation of matter.
B. 2H₂ + O₂ ⇒ NH₃ This option is wrong because in the reactants there is oxygen and it is not in the products.
C. 2Al₂O₃ ⇒ 2Na₂O This equation is not according to the law of conservation of matter, in the reactants there is aluminum and it is not in the products.
D. N₂ + 3H₂ ⇒ P₄O₁₀ This equation is not according to the law of conservation of matter.
The first thing you will need to do is find some information about your element. Go to the Periodic Table of Elements and click on your element. If it makes things easier, you can select your element from an alphabetical listing.
Use the Table of Elements to find your element's atomic number and atomic weight. The atomic number is the number located in the upper left corner and the atomic weight is the number located on the bottom, as in this example for krypton:
Krypton's data from the Table of Elements
Step 2 - The Number of Protons is...
The atomic number is the number of protons in an atom of an element. In our example, krypton's atomic number is 36. This tells us that an atom of krypton has 36 protons in its nucleus.
The interesting thing here is that every atom of krypton contains 36 protons. If an atom doesn't have 36 protons, it can't be an atom of krypton. Adding or removing protons from the nucleus of an atom creates a different element. For example, removing one proton from an atom of krypton creates an atom of bromine.
Step 3 - The Number of Electrons is...
By definition, atoms have no overall electrical charge. That means that there must be a balance between the positively charged protons and the negatively charged electrons. Atoms must have equal numbers of protons and electrons. In our example, an atom of krypton must contain 36 electrons since it contains 36 protons.
Electrons are arranged around atoms in a special way. If you need to know how the electrons are arranged around an atom, take a look at the 'How do I read an electron configuration table?' page.
An atom can gain or lose electrons, becoming what is known as an ion. An ion is nothing more than an electrically charged atom. Adding or removing electrons from an atom does not change which element it is, just its net charge.
For example, removing an electron from an atom of krypton forms a krypton ion, which is usually written as Kr+. The plus sign means that this is a positively charged ion. It is positively charged because a negatively charged electron was removed from the atom. The 35 remaining electrons were outnumbered by the 36 positively charged protons, resulting in a charge of +1.
Step 4 - The Number of Neutrons is...
The atomic weight is basically a measurement of the total number of particles in an atom's nucleus. In reality, it isn't that clean cut. The atomic weight is actually a weighted average of all of the naturally occurring isotopes of an element relative to the mass of carbon-12. Didn't understand that? Doesn't matter. All you really need to find is something called the mass number. Unfortunately, the mass number isn't listed on the Table of Elements. Happily, to find the mass number, all you need to do is round the atomic weight to the nearest whole number. In our example, krypton's mass number is 84 since its atomic weight, 83.80, rounds up to 84.
The mass number is a count of the number of particles in an atom's nucleus. Remember that the nucleus is made up of protons and neutrons. So, if we want, we can write:
Mass Number = (Number of Protons) + (Number of Neutrons)
For krypton, this equation becomes:
84 = (Number of Protons) + (Number of Neutrons)
If we only knew how many protons krypton has, we could figure out how many neutrons it has. Wait a minute... We do know how many protons krypton has! We did that back in Step 2! The atomic number (36) is the number of protons in krypton. Putting this into the equation, we get:
84 = 36 + (Number of Neutrons)
What number added to 36 makes 84? Hopefully, you said 48. That is the number of neutrons in an atom of krypton.
The interesting thing here is that adding or removing neutrons from an atom does not create a different element. Rather, it creates a heavier or lighter version of that element. These different versions are called isotopes and most elements are actually a mixture of different isotopes.
If you could grab atoms of krypton and count the number of neutrons each one had, you would find that most would have 48, others would have 47, some would have 50, some others would have 46, a few would have 44 and a very few would have 42. You would count different numbers of neutrons because krypton is a mixture of six isotopes.
In Summary...
For any element:
Number of Protons = Atomic Number
Number of Electrons = Number of Protons = Atomic Number
Number of Neutrons = Mass Number - Atomic Number
For krypton:
Number of Protons = Atomic Number = 36
Number of Electrons = Number of Protons = Atomic Number = 36
Number of Neutrons = Mass Number - Atomic Number = 84 - 36 = 48
Answer:
0.00916432 km/s
21648 inches/minute
Explanation:
1 kilometre / second =
2236.936 miles per hour
20.5/2236.9=0.00916432km/s
1 mile per hour =
1056 inches / minute
20.5×1056=21648 inches/minute
By wearing thick clothes, near in a furnace or something that is warm