Answer:
27.53 mL.
Explanation:
- Firstly, we need to calculate the no. of moles of HCl using the general law of ideal gas: <em>PV = nRT.</em>
where, P is the pressure of the gas in atm (P = 1.0 atm at STP).
V is the volume of the gas in L (4.48 L).
n is the no. of moles of the gas in mol.
R is the general gas constant (R = 0.0821 L.atm/mol.K),
T is the temperature of the gas in K (T = 273 K at STP).
<em>∴ n = PV/RT </em>= (1.0 atm)(4.48 L)/(0.0821 L.atm/mol.K)(273 K) = <em>0.1998 mol ≅ 0.12 mol.</em>
<em>∴ The concentration of 0.12 mol HCl in 400.0 mL water = n/V = </em>(0.12 mol)/(0.4 L) <em>= 0.499 ≅ 0.50 mol/L.</em>
- At equivalence: the no. of millimoles of HCl = the no. of millimoles of Sr(OH)₂.
<em>(MV)HCl = (xMV) Sr(OH)₂</em>
∴ The volume of Sr(OH)₂ = (MV)HCl/(xM) Sr(OH)₂ = (25.0 mL)(0.50 mol/L)/(2)(0.227 M) = 27.53 mL.
1. The half-life of the element is 22 years
2. The time taken for 308 g of the sample to decay to 4.8125 g is 132 years
<h3>Definition of half-life </h3>
Half-life is simply defined as the time taken for half of a material to decay.
<h3>1. How to determine the half-life </h3>
- Original amount (N₀) = 45 g
- Half of the original amount = 45 / 2 = 22.5 g
From the diagram, the time for 22.5 g is 22 years.
Thus, the half-life of the element is 22 years
<h3>2. How to determine the time </h3><h3>i. Determination of the number of half-lives </h3>
- Original amount (N₀) = 308 g
- Amount remaining (N) = 4.8125 g
- Number of half-lives (n) =?
2ⁿ = N₀ / N
2ⁿ = 308 / 4.8125
2ⁿ = 64
2ⁿ = 2⁶
n = 6
<h3>ii. Determination of the time </h3>
- Number of half-lives (n) = 6
- Half-life (t½) = 22 years
t = n × t½
t = 6 × 22
t = 132 years
See attached photo for diagram
Learn more about half life:
brainly.com/question/26374513
the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.
Explanation:
Gravitational potential energy
= mgh = (45kg)(9.81N/kg)(2m) = 882J.