1. Julius observes the chemical reaction between chalk and hydrochloric acid in a beaker. Which of the following will not cause the rate of reaction
а
to increase? *
a) breaking down the chalk into small pieces
b) cooling the chalk in a freezer
c) heating the hydrochloric acid on a hot plate
d) using a stirring rod to agitate the beaker's contents

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.