Answer: 8.1 days
Explanation:
Expression for rate law for first order kinetics is given by:

where,
k = rate constant
t = age of sample
a = let initial amount of the reactant = x
a - x = amount left after decay process=
a) to find rate constant
Half life is the amount of time taken by a radioactive material to decay to half of its original value.


b) for completion of one fourth of reaction



Thus after 8.1 days , one fourth of original amount will remain.
Answer:
Explanation:
Divide the mass by the density and the units of grams will cancel so youll end up with mL.
(52.757g)/(12.5g/mL) = 4.2mL
279 g * (1 mol/180.559g glucose) * (2 mol ethanol/1 mol glucose) * (46.068g ethanol/1mol) =
142 g ethanol produced
Answer:
-6.27 kj
Explanation:
Given data:
Energy released = ?
Mass of steam = 15 g
Initial temperature = 100°C
Final temperature = 0°C
Solution:
Specific heat capacity:
It is the amount of heat required to raise the temperature of one gram of substance by one degree.
Specific heat capacity of water is 4.18 j/g.°C
Formula:
Q = m.c. ΔT
Q = amount of heat absorbed or released
m = mass of given substance
c = specific heat capacity of substance
ΔT = change in temperature
ΔT = 0°C - 100°C = -100°C
Q = 15g × 4.18 j/g.°C × -100°C
Q = -6270 j
J to KJ:
-6270 j/1000 = -6.27 kj
Answer:

Explanation:
First, find the molar mass of calcium (Ca). This can be found on the Periodic Table.
Next, find the number of moles.
Avogadro's Number tells us the number of atoms in one mole.
Therefore, there are 6.023*10²³ atoms in 1 mole.
We have 6.023*10²³ atoms of calcium, so it must also be 1 mole of calcium.
Finally, find the mass. Set up a proportion using the molar mass of calcium.

Multiply. The moles (mol Ca) will cancel.


There are <u>40.08 grams </u>in 6.023*10²³ atoms of calcium.