You\'re looking for Ka, the dissociation constant, so you measure this by adding the substance to water. 1. Write the balanced equation HBrO + H2O = BrO- + H30+ 2. the pH is 4.95, so you know its acidic and there has to have hydronium as a product. if the pH was >7.0, there would be OH- instead. the pH is a measure of H ions, and to get the concentration, you simply do 10^(-pH). 10^(-4.95) = 1.12E-5 3. The equation for Ka is concentration of products/concentration of reactants. always look at the coefficients infront of the molecules in the reaction. in this case, it is [BrO-)][H3O+]/[HBrO] *liquids and solids are never included in this, only aqueous solutions and gases are* 4. Your concentration of H3O was found to be 1.12E-5, and because the H30 and BrO are in a 1:1 ration in the equation, the concentration for BrO is also 1.12E-5. The concentration for HBrO as a reactant is given, but the final concentration is 0.063-concentration of hydronium...but since the concentration of the hydronium is so small, it doesnt at all affect the final answer. 5. your equation for Ka=((1.12E- 5)(1.12E-5))/(0.063-1.12E-5). The final answer for your Ka is 2.0E-9 Hope this helps, please rate. Solution You\'re looking for Ka, the dissociation constant, so you measure this by adding the substance to water. 1. Write the balanced equation HBrO + H2O = BrO- + H30+ 2. the pH is 4.95, so you know its acidic and there has to have hydronium as a product. if the pH was >7.0, there would be OH- instead. the pH is a measure of H ions, and to get the concentration, you simply do 10^(-pH). 10^(-4.95) = 1.12E-5 3. The equation for Ka is concentration of products/concentration of reactants. always look at the coefficients infront of the molecules in the reaction. in this case, it is [BrO-)][H3O+]/[HBrO] *liquids and solids are never included in this, only aqueous solutions and gases are* 4. Your concentration of H3O was found to be 1.12E-5, and because the H30 and BrO are in a 1:1 ration in the equation, the concentration for BrO is also 1.12E-5. The concentration for HBrO as a reactant is given, but the final concentration is 0.063-concentration of hydronium...but since the concentration of the hydronium is so small, it doesnt at all affect the final answer. 5. your equation for Ka=((1.12E- 5)(1.12E-5))/(0.063-1.12E-5). The final answer for your Ka is 2.0E-9 Hope this helps, please rate..