Acetic acid (CH3COOH) is a weak acid while methylamine (CH3NH2) is a weak base. During an acid base reaction, an acid tends to lose a proton while a base tends to accept a proton. The reaction at equilibrium is as follows:
↔
Hence the species in equilibrium are:
Acetate anion: CH3COO-
Methyl ammonium cation: CH3NH3+
Answer:
Net ionic equation for the reaction between MgCl₂ and NaOH in water:
.
Net ionic equation for the reaction between MgSO₄ and BaCl₂ in water:
.
Explanation:
Start by finding the chemical equations for each reaction:
MgCl₂ reacts with NaOH to form Mg(OH)₂ and NaCl. This reaction is a double decomposition reaction (a.k.a. double replacement reaction, salt metathesis reaction.) This reaction is feasible because one of the products, Mg(OH)₂, is weakly soluble in water and exists as a solid precipitate.
.
MgSO₄ reacts with BaCl₂ in a double decomposition reaction to produce BaSO₄ and MgCl₂. Similarly, the solid product BaSO₄ makes this reaction is feasible.
.
How to rewrite a chemical equation to produce a net ionic equation?
- Rewrite all reactants and products that ionizes completely in the solution as ions.
- Eliminate ions that exist on both sides of the equation to produce a net ionic equation.
Typical classes of chemicals that ionize completely in water:
- Soluble salts,
- Strong acids, and
- Strong bases.
Keep the formula of salts that are not soluble in water, weak acids, weak bases, and water unchanged.
Take the first reaction as an example, note the coefficients:
- MgCl₂ is a salt and is soluble in water. Each unit of MgCl₂ can be written as
and 
. - NaOH is a strong base. Each unit of NaOH can be written as
and 
. - Mg(OH)₂ is a weak base and should not be written.
- NaCl is a salt and is soluble in water. Each unit of NaCl can be written as and
.
.
Ions on both sides of the equation:
- , and
.
Add the state symbols:
.
For the second reaction:
.
.
.
<span>Avogadro's number
represents the number of units in one mole of any substance. This has the value
of 6.022 x 10^23 units / mole. This number can be used to convert the number of
atoms or molecules into number of moles.
</span><span>7.5 X10^23 molecules of H2SO4 ( 1 mol / 6.022x10^23 molecules ) (98.08 g / 1 mol ) = 122.15 grams H2SO4</span>
To compute the energy, Q, needed to melt a certain amount of ice, n, in moles, we have
where the latent heat of fusion for ice is equal to 6.009 kJ/mol.
Now, since we have a 20.0 lb ice, we must first convert its mass to grams. Thus mass = (20.0)(1000)(0.4536) = 9072 g.
To find the number of moles present, we must recall that the molar mass of water (ice) is equal to <span>1.00794(2) + </span><span>15.9994 </span>≈ 18.01 g/mol. Hence, we have
Now, to compute for the molar heat of fusion, Q,
Therefore, the amount of heat needed to melt the 20-lb bag of ice is equal to 3026.9 kJ.
Answer: 3026.9 kJ
