The number of grams of NaOH that are needed to make 500 ml of 2.5 M NaOH solution
calculate the number of moles =molarity x volume/1000
= 2.5 x 500/1000 = 1.25 moles
mass = moles x molar mass of NaOH
= 1.25 x40= 50 grams of NaOH
Hope u do well :) ik this maybe hard but you’ll get through it , the answer is D !
This is a chemical reaction because a precipitate (solid) was formed from 2 liquids, and there was a color change as well
Answer:
c
Explanation:
three or more atoms make up one compound
Answer : The initial mass of the sample is, 31.9 mg
Explanation :
Half-life = 4 days
First we have to calculate the rate constant, we use the formula :



Now we have to calculate the initial mass of sample.
Expression for rate law for first order kinetics is given by:

where,
k = rate constant = 
t = time passed by the sample = 12 days
a = initial amount of the reactant = ?
a - x = amount left after decay process = 4 mg
Now put all the given values in above equation, we get


Therefore, the initial mass of the sample is, 31.9 mg