Answer:
Do you have a picture
or can you state the reaction
Answer:
The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. Dispersion forces are present between any two molecules (even polar molecules) when they are almost touching.
Thus <em>PROTON movement causes partial positive & negative charges creating
</em>
<em>attraction</em> will be crrt
Freezing point. because toxicity is a chemical property as well as pH and flammability is dependent on the items chemical composition <span />
Answer:
- <u><em>It is positive when the bonds of the product store more energy than those of the reactants.</em></u> (the second statement)
Explanation:
ΔHf is the change of enthalpy during the reaction, which is equal to the sum of enthaply changes of the products less the sum of the enthalpy changes of the reactants.
- ΔHf = ∑ (ΔH products) - ∑ (ΔH reactants)
Also, ΔHrxn, per definition, is the potential chemical energy stored in the bonds of the products less the chemical potential energy stored in the bonds of the reactants.
Then, when the potential chemical energy stored in the bonds of the products is greater than the chemical potential energy stored in the bonds of the reactants ΔHrxn is positive.
Hence, you conclude that ΔHf is positive when the bonds of the product store more energy than those of the reactants (second statement from the choices).
Some brief comments about the other statements:
- The standard enthalpy of formation, ΔHf, is zero for an element in its standard state, not for a compound.
- For a compound the enthalpy of formation at 25ºC and 1 atm (the standard state) may be positive or negative.
- Also, note that the standard state for any element is not liquid: some are solids, some are gases, and some are liquids at 25ºC and 1 atm.
