A substance is dissolved in water, and the temperature of the surroundings decreases. Is this process exothermic or endothermic? Explain your reasoning in 3-5 sentences. Help PLease!!

What volume of a 2.00 m stock solution of naoh is needed to prepare 150. ml of 0.40 m solution?

Answer asap need by wednesday morning explain how a buffer works, using an ethanoic acid/sodium ethanoate system including how the system resists changes in ph upon addition of a small amount of base and upon addition of a small amount of acid respectively. include the following calculations in your i. calculate the ph of a solution made by mixing 25cm3 0.1m ch3cooh and 40cm3 0.1m ch3coo-na+. [ka = 1.74 x 10-5 m] ii. calculate the ph following the addition of a 10cm3 portion of 0.08 m naoh to 500cm3 of this buffer solution. iii. calculate the ph following the addition of a 10cm3 portion of 0.08 m hcl to 200cm3 of the original buffer solution.

#20 which type of bond is formed when bases pair in dna? ionic bond covalent bond coordinate bond hydrogen bond