4. test your understanding of titrations. a) write a balanced equation for the neutralization of aqueous strontium hydroxide with aqueous hydrochloric acid. b) a chemist finds a strontium hydroxide solution in lab, but the concentration of this solution is not labeled. a 25.00 ml sample of strontium hydroxide solution is placed in a flask. it takes the addition of 30.00 ml of 0.2695 m hcl to reach the equivalence point. i. define equivalence point. ii. what is the molarity of the strontium hydroxide solution? [0.1617 m] iii. what is the molarity of aqueous h+ ions in the 0.2695 m hcl solution used in this titration? (note- aqueous h+ ions are also known as h3o+ ions) [0.2695 m] iv. you will learn more about ph later in the semester. it is a measure of the acidity or basicity of a substance. if ph = -log [h+] or -log[h3o+], what is the ph of the aqueous hcl solution? include correct significant figures! [ph = 0.5694]

The following reaction shows the products when sulfuric acid and aluminum hydroxide react. al(oh)3 + h2so4 → al2(so4)3 + h2o the table shows the calculated amounts of reactants and products when the reaction was conducted in a laboratory. initial mass and yield sulfuric acid aluminum hydroxide initial amount of reactant 40 g 15 g theoretical yield of water from reactant 14.69 g 10.38 g what is the approximate amount of the leftover reactant? 11.73 g of sulfuric acid 10.33 g of sulfuric acid 11.12 g of aluminum hydroxide 13.67 g of aluminum hydroxide

Straightforward questions answered in the powerpoint slidesreaction: heating the starting materials under refluxwhat does it mean to heat under reflux? why do we choose water as the reflux solvent? what are boiling chips used for? why do we put a condenser on top of the reaction? why do we add heat and let the reaction stir for 30 minutes? why do we add sulfuric acid to the reaction after it cools as opposed to when it’s still hot? separation: filtration of precipitatewhy don’t we do an aqueous and organic extraction in the separatory funnel? why do you rinse the salicylic acid on the filter with ice cold water? purification: recrystallization of salicylic acid (no hot filtration needed)what is the difference in the amount of room temperature water vs. boiling water needed to dissolve the salicylic acid (assume a 1.2 gram yield of salicylic acid)? remember, in the lab if you need x ml of boiling water to dissolve a solid, then you should add a little more (definitely no more than 1.5 times the theoretical amount) to ensure it doesn’t recrystallize prematurely.analysis: melting point of salicylic acidwhat can you conclude if the melting point of the salicylic acid you just synthesized is 152-155oc and the 1: 1 mix of your product and “synthetic” salicylic acid is 151-154oc?

An electron moved from shell n = 2 to shell n = 1. what most likely happened during the transition? a fraction of a photon was added. a photon of energy was absorbed. a fraction of a photon was removed. a photon of energy was released.