A fossil is any natural evidence of prehistoric life that provides some idea of the size, shape, or form of the organism. A foss
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Answer:
C. hydration number
Explanation:
When we dissolve an ionic compound (a charged species) the charges can <u>interact with the water molecule</u>. In the case of <u>cations</u> (positive charges) the negative <u>dipole</u> of water (generated in the oxygen) will interact with the positive charge at the same time the <u>anions</u> (negative charges) the positive <u>dipole</u> of water (generated in the hydrogen).
The amount of water molecules that can interact with a single ion (cation or anion) is called <u>hydration number</u>. In the example, we have a hydration number of "4" for the sodium cation.
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Answer:
Explanation:
We are asked to find how many kilojoules of energy would be required to heat a block of aluminum.
We will use the following formula to calculate heat energy.
The mass (m) of the aluminum block is 225 grams and the specific heat (c) is 0.897 Joules per gram degree Celsius. The change in temperature (ΔT) is the difference between the final temperature and the initial temperature.
- ΔT = final temperature - inital temperature
The aluminum block was heated from 23.0 °C to 73.5 °C.
- ΔT= 73.5 °C - 23.0 °C = 50.5 °C
Now we know all three variables and can substitute them into the formula.
- m= 225 g
- c= 0.897 J/g° C
- ΔT= 50.5 °C
Multiply the first two numbers. The units of grams cancel.
Multiply again. This time, the units of degrees Celsius cancel.
The answer asks for the energy in kilojoules, so we must convert our answer. Remember that 1 kilojoule contains 1000 joules.
Multiply by the answer we found in Joules.
The original values of mass, temperature, and specific heat all have 3 significant figures, so our answer must have the same. For the number we found, that is the tneths place. The 9 in the hundredth place tells us to round the 1 up to a 2.
Approximately <u>10.2 kilojoules</u> of energy would be required.
Answer:
The molar mass of the compound is:- 168.82 g/mol
The molar mass of the gas is:- 16.38 g/mol
Explanation:
(a)
Using ideal gas equation as:
where,
P is the pressure
V is the volume
n is the number of moles
T is the temperature
R is Gas constant having value = 0.0821 L.atm/K.mol
Also,
Moles = mass (m) / Molar mass (M)
Density (d) = Mass (m) / Volume (V)
So, the ideal gas equation can be written as:
Given that:-
Pressure = 20 kPa = 20000 Pa
The expression for the conversion of pressure in Pascal to pressure in atm is shown below:
P (Pa) = P (atm)
20000 Pa = atm
Pressure = 0.1974 atm
Temperature = 330 K
d = 1.23 kg/m³ = 1.23 g/L
Molar mass = ?
Applying the equation as:
0.1974 atm × M = 1.23 g/L × 0.0821 L.atm/K.mol × 330 K
⇒M = 168.82 g/mol
<u>The molar mass of the compound is:- 168.82 g/mol</u>
(b)
Given that:
Pressure = 152 Torr
Temperature = 298 K
Volume = 250 cm³ = 0.25 L
Using ideal gas equation as:
R =
Applying the equation as:
152 Torr × 0.25 L = n × 62.3637 L.torr/K.mol × 298 K
⇒n = 0.002045 moles
Given that :
Mass of the gas = 33.5 mg = 0.0335 g
Molar mass = ?
The formula for the calculation of moles is shown below:
Thus,
<u>The molar mass of the gas is:- 16.38 g/mol</u>