Answer:
760 uM
Explanation:
<em>A biochemist carefully measures the molarity of magnesium ion in 47, mL of cell growth medium to be 97 uM. Unfortunately, a careless graduate student forgets to cover the container of growth medium and a substantial amount of the solvent evaporates. The volume of the cell growth medium falls to 6.0 mL. Calculate the new molarity of magnesium ion in the cell growth medium Be sure your answer has the correct number of significant digits.</em>
The problem here is that the amount of magnesium ion remains the same irrespective of the volume.
Amount of magnesium in the growth medium = <em>molarity x volume</em>
= 97 x 
x 47 x 
= 4.559 x
Then, the volume reduced to 6.0 mL, the new molarity becomes;
<em>molarity = mole/volume </em>
= 4.559 x /6 x = 7.598333 x 
M = 759.83333 uM
To the correct number of significant digits = 760 uM
Answer:
The 3rd answer down.
Na²O (sodium oxide) will be a base when exposed to water H²O
Explanation:
Sodium Oxide Na²O, will become Sodium Hydroxide after being exposed to water (at 80% I believe).
The oxygen ion in Na²O has 2 extra electrons which makes it highly charged and very attractive to hydrogen ions. The attraction is so strong that when Na²O comes in contact with H²O, the O(-2) strips off a hydrogen from water, forming 2 x OH ions which of course are still strongly basic.
B)
<span>
a subatomic particle with no electric charge, found in the nucleus of an atom </span>
Exothermic reactions:
1) release heat to the surroundings
2) the change of enthalpy, ΔH, is negative: ΔH < 0
3) the temperature of the system increases
With that you can conclude about every equation given:
<span>NH3(g) + 12.0 kcal → ½N2(g) + 3/2 H2(g) : is not exothermic because heat in the side of the reactants means that heat is being used, not released.
C(graphite) → C(diamond), ΔH = - 0.45 kcal : is exothermic because ΔH is negative
C + 2S → CS2, ΔH = 27,550 cal: is not exothermic because ΔH is positive
CH4 + 2O2 → CO2 + 2H2O + 212,800 cal : is exothermic because heat appears as a product of the reaction, which means that it is released.
2H2O → 2H2 + O2, ΔH = +58 kcal : is not exothermic because ΔH is positive.</span>
