Answer:
a
Explanation:
got it right in study island xD
During a combustion reaction the carbon in a hydrocarbon compound is paired with Oxygen (O2) in the air to form Carbon-Dioxide (CO2), whilst the Hydrogen too pairs with Oxygen to form water vapour (H2O). Heat is also produced during this reaction.
Answer:
One of the bonds in nitrate is shorter than the other two.
Explanation:
We would firstly need to draw the Lewis structure for nitrate anion. To do this, let's follow the standard steps:
- calculate the total number of valence electrons: five from nitrogen, each oxygen contributes 6, so a total of 18 from oxygen atoms, as well as one from the negative charge, we have a total of 24 valence electrons;
- assign the central atom, usually this is the atom which is single; in this case, we have nitrogen as our central atom;
- assign single bonds to all the terminal atoms (oxygen atoms);
- assign octets to the terminal atoms and calculate the number of electrons assigned;
- the number of electrons assigned is 24, so no lone pairs are present on nitrogen;
- calculate the formal charges: each oxygen has a formal charge of -1 (formal charge is calculated subtracting the sum of lone pair electrons and bonds from the number of valence electrons of that atom); nitrogen has a formal charge of +2;
- nitrogen doesn't have an octet as well, so we'll both minimize its formal charge and make it obtain an octet if we make one double bond N=O.
Therefore, we may have 3 resonance structures, as this double bond might be formed with any of the 3 oxygen atoms.
By definition, double bonds are shorter than single ones, so one of the bonds is shorter than the other two.
A. The elements melting point temperatures.
Answer:
ΔH of reaction is -856 kJ/mol
Explanation:
The property ΔH is property which can be added to find the net change in enthalpy of reaction.
ΔH of first reaction is -665.9 kJ/mol
ΔH of second reaction is 190.1 kJ/mol
carefully looking at the third equation,
it is first reaction - second reaction.
thus, by Hess's law,
<em>Hess's Law of Constant Heat Summation (or just Hess's Law) states that regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes.</em>
ΔH of third reaction is = 
ΔH = -856 kJ/mol
