A 0.500-g sample containing Na2CO3 plus inert matter is analyzed by adding 50.0 mL of 0.100 M HCl, a slight excess, boiling to remove CO2, and then back-titrating the excess acid with 0.100 M NaOH. If 5.6 mL NaOH is required for the back-titration, what is the percent Na2CO3 in the sample?

Select the correct answer from each drop-down menu. daniel and sanya are scientists. daniel is studying whether the increasing frequency of tropical storms is affecting coastal erosion. sanya is investigating whether the discharge from industrial plants has any impact on the ph concentration of freshwater swamps in the surrounding area. which fields of science are daniel’s and sanya’s studies most closely related to? daniel’s field of study is related to science, and sanya’s field of study is related to .

Calculate the ratio of h+ ions to oh– ions at a ph = 7. find the concentration of h+ ions to oh– ions listed in table b of your student guide. then divide the h+ concentration by the oh– concentration. record this calculated ratio in table a of your student guide. compare your approximated and calculated ratios of h+ ions to oh– ions at a ph = 7. are they the same? why or why not? record your comparison in table a. what is the concentration of h+ ions at a ph = 7? mol/l what is the concentration of oh– ions at a ph = 7? mol/l what is the ratio of h+ ions to oh– ions at a ph = 7? : 1

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?