General Chemistry Answers

Consider the reaction when aqueous solutions of sodium sulfide and calcium chloride are combined. The net ionic equation for this reaction is:

A laser pulse with a wavelength of 525 nm

nm contains 4.40 mJ

mJ of energy. How many photons are in the laser pulse?

Why was CoCl2.6H20 used as starting in synthesis of [Co(en)]Cl3??NaCl?3H2O and not CoCl3?

Determine the solubility of BaF₂ in g/L if K_sp of BaF₂ = 1 × 10^-6. (Please give your answer with 2 significant figures.)

A solution contains 0.0021 M Ag⁺ and 1.6 x 10^-5 M Zn²⁺, and the ions need to be separated. For this purpose  is added to the solution so that both Ag₂CO₃ (K_sp = 8.1 x 10^-12) and ZnCO₃ (K_sp = 1.0 x 10^-10) can precipitate from the solution. What will the concentration of be just before the first salt starts to precipitate. (Please give your answer with 2 significant figures.)

What mass of NaF must be added to 1.0 L of 0.0025 M Pb²⁺ to initiate precipitation of PbF₂(s)? (K_sp of PbF₂ is 3.3 × 10^-8; assume no volume change on addition of NaF.) (Please give your answer with 2 significant figures.)

When SrF₂, strontium fluoride, is added to water, the salt dissolves to a very small extent according to the reaction below. At equilibrium the concentration of Sr²⁺ is found to be 0.00196 M. What is the value of K_sp for SrF₂? (Please give your answer with 2 significant figures.)