Answer:
48 g/mol
Explanation:
Step 1: Calculate the mass of the gas (m)
According to the law of conservation of mass, the mass of the solid before the decomposition must be equal to the sum of the masses of the solid residue and the gas
mSolid = mResidue + mGas
mGas = mSolid - mResidue = 4.73 g - 4.10 g = 0.63 g
Step 2: Convert 320 cm³ to L
We will use the conversion factor 1 L = 1000 cm³.
320 cm³ × 1 L/1000 cm³ = 0.320 L
Step 3: Calculate the moles of gas (n)
The gas is at room temperature (298.15 K) and room pressure (1 atm). We can calculate the moles of gas using the ideal gas equation.
P × V = n × R × T
n = P × V/R × T
n = 1 atm × 0.320 L/(0.0821 atm.L/mol.K) × 298.15 K = 0.0131 mol
Step 4: Calculate the molecular mass of the gas (M)
We will use the following expression.
M = m/n = 0.63 g/0.0131 mol = 48 g/mol
Answer:
D) both a and c are correct
Explanation:
The reaction rate is a measure of the speed of a chemical reaction. The factors that affects the rate of a chemical reaction are itemised below:
- Nature of the reactants
- Concentration of the reactants or pressure(if gaseous)
- Temperature
- Presence of catalyst
- Sunlight
Our concern here is temperature. Temperature affects a reaction considerably. Average kinetic energy is directly proportional to the temperature of the reacting particles. When the temperature of a reacting system is increase, the frequency of ordinary and effective collisions per unit time increases. A decrease in temperature implies that the number of collisions also decreases.
Explanation:
An object in motion <u>stays</u> <u>at</u> motion An object <u>at</u> <u>rest</u> stays at rest unless acted by an <u>external</u> force.
[ Newton's 1st law of motion ]
Using the exponential decay model; we calculate "k"
We know that "A" is half of A0
A = A0 e^(k× 5050)
A/A0 = e^(5050k)
0.5 = e^(5055k)
In (0.5) = 5055k
-0.69315 = 5055k
k = -0.0001371
To calculate how long it will take to decay to 86% of the original mass
0.86 = e^(-0.0001371t)
In (0.86) = -0.0001371t
-0.150823 = -0.0001371 t
t = 1100 hours
