It is very important<span> to know the shape of a molecule if one is to understand its reactions. It is also desirable to have a simple method to predict the geometries of compounds. For main group compounds, the </span>VSEPR<span> method is such a predictive tool and unsurpassed as a handy predictive method.</span>
Answer:
Molar mass = 0.09 × 10⁴ g/mol
Explanation:
Given data:
Mass = 0.582 g
Volume = 21.3 mL
Temperature = 100°C
Pressure = 754 mmHg
Molar mass = ?
Solution:
(21.3 /1000 = 0.0213 L)
(100+273= 373 K)
(754/760 = 0.99 atm)
PV = nRT
n = PV/RT
n = 0.99 atm × 0.0213 L / 0.0821 atm. L. mol⁻¹. k⁻¹ × 373 K
n =0.02 mol/ 30.6
n = 6.5 × 10⁻⁴ mol
Molar mass = Mass/ number of moles
Molar mass = 0.582 g / 6.5 × 10⁻⁴ mol
Molar mass = 0.09 × 10⁴ g/mol
1. <span>The answer should be combustion
2. </span><span>Water is known to successfully dissolve both acids and bases, and water is considered a universal solvent.
3. The answer should be balanced.
Hope this helps :)
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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.
