Phosphoric acid is a triprotic acid with the p K a pKa values p K a 1 = 2.148 pKa1=2.148 , p K a 2 = 7.198 pKa2=7.198 , and p K a 3 = 12.375 pKa3=12.375 . You wish to prepare 1.000 L of a 0.0300 0.0300 M phosphate buffer at pH 7.460 7.460 . To do this, you choose to mix the two salt forms involved in the second ionization, NaH 2 PO 4 NaH2PO4 and Na 2 HPO 4 Na2HPO4 , in a 1.000 L volumetric flask and add water to the mark. What mass of each salt will you add to the mixture?

Imagine that you’re getting ready to move to a new city. when people move, they are influenced by push factors and pull factors, and you have many reasons for your move. which of the following factors is an example of a pull factor? a. wanting to move because you’ve found a great new school somewhere new b. needing to move because there are not enough resources in your old hometown c. being forced to move because your old home is gone d. having to move because there are no jobs in your current hometown

3. how much energy in joules is required to evaporate .0005 kg of liquid ammonia to vapor at the same temperature? 4. how much energy ( in megajoules ) is given up by .75 kg of water at 0c when it freezes to form ice at 0c? 5. explain how heat works between and at critical temperatures?

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?