Ka of a weak acid HX is 6.72 × 10–7. During a titration, an analyte solution containing a mixture of [HX] and [X–] has the ratio of [X–]/[HX] = 1.75. What is the pH of the analyte solution? Assume the solution is in its buffering region, where pH of the solution can be approximated by: pH = pKa + log([X–]/[HX])

Measuring which physical property is most likely to produce the most precise results when trying to identify a substance

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size

The chemical equation below shows the reaction of sodium (na) and chlorine (cl) to form sodium chloride (nacl). 2na + cl2 → 2nacl in this equation, which of the following is a reactant? i. sodium ii. chlorine iii. sodium chloride