Answer:
Time taken 172.8 years
Explanation:
Given data:
Total amount of strontium-90 = 1000.0 g
Amount left = 15.625 g
Half life of strontium = 28.8 years
Time taken = ?
Solution:
Number of half lives:
At time zero = 1000.0 g
At first half life = 1000.0g/2 = 500 g
At second half life = 500 g/2 = 250 g
At third half life = 250 g/ 2 = 125 g
At 4th half life = 125 g/ 2= 62.5 g
At 5th half life = 62.5 g/2 = 31.25 g
At 6th half life = 31.25 g / 2 = 15.625 g
Time taken:
Time taken = number of half lives × half life
Time taken = 6×28.8 years
Time taken = 172.8 years
Answer:
106 mL
Explanation:
In order to be able to answer this question, you must understand what the density of a substance tells you.
The density of a substance is nothing more than the mass of that substance that occupies one unit of volume.
In your case, the density of ethanol is given in Grams per milliliter, which means that one unit of volume will be
1 mL
.
So, ethanol has a density of
0.785 g mL
−
1
, which is equivalent to saying that if you take exactly
1 mL
of ethanol and weigh it, you will end up with a mass of
0.785 g
.
Now, you know that the volume you're using has a mass of
83.3 g
. Well, if you get
0.785 g
for every
1 mL
of ethanol, it follows that this much mass will correspond to a volume of
83.3
g ethanol
⋅
ethanol's density
1 mL
0.785
g ethanol
=
106.11 mL
Rounded to three sig figs, the answer will be
V
ethanol
=
106 mL
Hope this helps
• Before the balloon was placed inside the hot water, the pressure was the same inside and outside the balloon. The hot water raised the kinetic energy of the air molecules inside the balloon, expanding the balloon, through thermal expansion.
• (1) the pressure of air inside the balloon increased, (2) the volume of the inside of the balloon increased as well, and (3) the temperature of the balloon increased. Note that pressure and volume are inversely proportional, and pressure and temperature are directly proportional. Therefore as the temperature increases, the pressure inside will increase, causing an increase in the volume. At a certain point though the volume will increase too much as to cause a significant decrease in pressure.
• The air molecules will gain kinetic energy, hence (1) increasing the molecules's speed, and (2) heating the air molecules.
Answer:
Carbon dioxide is a compound
Explanation:
It is formed by chemical combination of carbon and oxygen atoms
Answer:
300 mL
Explanation:
the unit formula of calcium phosphate is Ca3(PO4)2
molar mass of Ca3(PO4)2 = (3×40 + 2×31 + 8×16) g/mol = 310 g/mol
n = m/M = 35 g/(310 g/mol)
c = n/V
V = n/c = [35 g/(310 g/mol)]/0.375 mol/L
V = 0.30 L = 300 mL
