Answer:
12.50g
Explanation:
T½ = 2.5years
No = 100g
N = ?
Time (T) = 7.5 years
To solve this question, we'll have to find the disintegration constant λ first
T½ = In2 / λ
T½ = 0.693 / λ
λ = 0.693 / 2.5
λ = 0.2772
In(N/No) = -λt
N = No* e^-λt
N = 100 * e^-(0.2772*7.5)
N = 100*e^-2.079
N = 100 * 0.125
N = 12.50g
The sample remaining after 7.5 years is 12.50g
Answer:
New volume is 25.0 mL
Explanation:
Let's assume the gas sample behaves ideally.
According to combined gas law for an ideal gas-
where, 
and 
represent initial and final pressure respectively
and 
represent initial and final volume respectively
and 
represent initial and final temperature (in kelvin) respectively
Here, 
, 
, 
and 
So, 
So, the new volume is 25.0 mL
Answer:
317 g
Explanation:
Cu + 2HCl --> CuCl2 +H2
1 : 2 1 : 1
1 mole of Cu = 63.5 g
1 mole of H2 = 2g
1 mole Cu produces = 1 mole of H2
63.5 g of Cu produces = 2 g of H2
So
10 g of H2 will be produced from = (63.5/2)*10 = 317 g of Copper
Answer:
88.5 g/m is the molar mass for the gas
Explanation:
We need the Ideal Gases Law equation to solve this:
P . V = n . R . T
Pressure (P) = 10 Torr
We must convert to atm → 10 Torr / 760 Torr = 0.0131 atm
Volume (V) = 255 mL
We must convert to L → 255 mL / 1000 = 0.255 L
n = number of moles
moles = mass in g / molar mass
12.1 mg/ 1000 = 0.0121 g
T° = 25°C + 273K = 298K
R = 0.082 L.atm /mol.K
Let's replace the values
0.0131 atm . 0.255L = 0.0121 g / x . 0.082 L.atm /mol.K . 298K
(0.0131 atm . 0.255L) / (0.082 L.atm /mol.K . 298K) = 0.0121 g / x
1.367×10⁻⁴ /mol = 0.0121 g / x
x = 0.0121 g / 1.367×10⁻⁴ mol = 88.5 g/m
