NH4Br has been dissolved into 1 L of water at 25 degrees celcius. the solution has a pH of 5.16. calculate number of grams of NH4Br.

I don't even know how to write the equation for this. Could someone please write the water + NH4 equation for me. Thanks :)

NH4^+ + HOH ==> NH3 + H3O^+

Ka = Kw/Kb = (H3O^+)(NH3)/(NH4^+).
You know Kw and Kb, and pH, you can calculate (H3O^+), (NH3) is the same, (NH4^+) = solve for this. Then M = moles/L to solve for moles and g = mols x molar mass to solve for grams.

By the way, not the correct spelling of celsius.

Thanks a lot Dr Bob :)

The equation for the dissociation of NH4Br in water is as follows:

NH4Br (s) → NH4+ (aq) + Br- (aq)

In this equation, NH4Br is a solid salt that dissociates into its ions, NH4+ and Br-, when dissolved in water.

To calculate the number of grams of NH4Br present in the solution, we need to understand the relationship between pH and the concentration of NH4+ ion in solution.

The pH of a solution is a measure of its acidity or alkalinity. In this case, since the pH is 5.16, the solution is slightly acidic. The acidic nature of the solution is due to the presence of NH4+ ions, as they can act as a weak acid and release H+ ions into the solution.

NH4+ (aq) + H2O (l) → NH3 (aq) + H3O+ (aq)

This equation represents the equilibrium between NH4+ and NH3 (ammonium and ammonia) in water. The NH4+ ion acts as a weak acid, donating a proton to water and forming NH3 (ammonia) and H3O+ (hydronium) ions.

Since we know the pH of the solution and the equation for the dissociation of NH4+, we can now calculate the concentration of NH4+ ions in the solution.

pH = -log [H3O+]

The concentration of NH4+ ions is equal to the concentration of H3O+ ions produced from the dissociation of NH4+, as they are in a 1:1 ratio.

[H3O+] = 10^(-pH)

Therefore, [NH4+] = [H3O+] = 10^(-5.16)

To convert the concentration of NH4+ ions into grams of NH4Br, we need to know the molar mass of NH4Br. The molar mass of NH4Br is 97.94 g/mol.

Knowing the molar mass, we can calculate the number of moles of NH4Br using the formula:

moles NH4Br = concentration of NH4+ (mol/L) x volume of solution (L)

Since we were given that NH4Br was dissolved into 1 L of water, the volume of the solution is 1 L.

moles NH4Br = [NH4+] x volume of solution

moles NH4Br = [NH4+] x 1 L

Finally, to get the number of grams of NH4Br:

grams NH4Br = moles NH4Br x molar mass NH4Br

Using all the information and the calculations above, you can find the number of grams of NH4Br in the solution.