Answer:
A) 900 J
B) 27.96 J
C) 1,628 J ≅ 1.63 kJ
Explanation:
The heat absorbed by the metal (silver) - or energy required to heat it - is calculated as:
heat = mass x Cp x ΔT
Where Cp is the heat capacity (0.24 J/°C ·g) and ΔT is the change in temperature (final T - initial T).
A) Given:
mass = 150.0 g
final T = 298 K = 25°C
initial T = 273 K = 0°C
We calculate the energy in J to raise the temperature:
heat = mass x Cp x (final T - initial T)
= 150 .0 g x 0.24 J/°C ·g x (25°C - 0°C )
= 900 J
B) Given:
moles Ag= 1.0 mol
ΔT = 1.08°C
We first calculate the mass of silver (Ag) by multiplying the moles of Ag by the molar mass of Ag (MM = 107.9 g/mol)
mass = moles x MM = 1.0 mol Ag x 107.9 g/mol Ag = 107.9 g
Then, we calculate the heat required:
heat = mass x Cp x ΔT = 107.9 g x 0.24 J/°C ·g x 1.08°C = 27.96 J
C) Given:
heat = 1.25 kJ = 1,250 J
final T = 15.28°C
initial T = 12.08°C
We first calculate the change in temperature:
ΔT = final T - initial T = 15.28°C - 12.08°C = 3.2°C
Then, we calculate the mass of silver:
mass = heat/(Cp x ΔT) = 1,250 J/(0.24 J/°C ·g x 3.2°C) = 1,628 J ≅ 1.63 kJ
This is actually known as the fourth state of matter which is the<em> plasma</em>. The plasma is basically a hot ionized gas. It consists of equal number of protons and electrons. This can be obtained by subjecting a gas to a high energy, for example, a laser beam. The energy from the laser beam causes a rapid energy increase of the atoms, such that they become ionized.
Answer: 6.6 ml
Explanation:
If you had a 0.200 L solution containing 0.0140 M of Fe3+(aq), and you wished to add enough 1.27 M NaOH(aq) to precipitate all of the metal, what is the minimum amount of the NaOH(aq) solution you would need to add? Assume that the NaOH(aq) solution is the only source of OH−(aq) for the precipitation.
You have 0.014X0,2 = 0,0028 moles of Fe ion.
You need 0,0028 X 3 = 00084 moles of OH
The NaOH is 1.27 moles/liter
0.084/1.27 = 6.6 ml
Answer:
Kₐ = 5.7 x 10⁻⁵
Explanation:
The equilbrium for this acid is
HC₃H₃CO₂ + H2O ⇄ H₃O⁺ + C₃H₃CO₂ ⁻ ,
and the equilibrium constant for acrylic acid is given by the expression:
Kₐ = [ H₃O⁺][ C₃H₃CO₂⁻ ] / [ HC₃H₃CO₂ ]
Since the pH of the 0.23 M solution is known , we can calculate [ H₃O⁺].
The ][ C₃H₃CO₂⁻ ] is equal to [ H₃O⁺] from the above equilibria (1:1)
Finally [ HC₃H₃CO₂ ] is known.
pH = - log [ H₃O⁺]
taking antilog to both sides of the equation
10^-pH = [ H₃O⁺]
Substituting
10^-2.44 = [ H₃O⁺] = 3.6 x 10⁻³
[ C₃H₃CO₂⁻ ] = 3.6 x 10⁻³
Kₐ = ( 3.6 x 10⁻³ ) /0 .23 = 5.7 x 10⁻⁵
Answer:
2 atoms
Explanation:
There are 2 atoms in element NaCl. This is because there is 1 atom of Na (sodium) and 1 atom of Cl (chlorine) in each NaCl molecule. Elements by themselves do not have a "number of atoms"- if you're talking about the atomic number, it's the number of protons (or electrons in a neutral atom) of an element.
