<h3>Answer:</h3>
a) Moles of Caffeine = 1.0 × 10⁻⁴ mol
b) Moles of Ethanol = 4.5 × 10⁻³ mol
<h3>Solution:</h3>
Data Given:
Mass of Caffeine = 20 mg = 0.02 g
M.Mass of Caffeine = 194.19 g.mol⁻¹
Molecules of Ethanol = 2.72 × 10²¹
Calculate Moles of Caffeine as,
Moles = Mass ÷ M.Mass
Putting values,
Moles = 0.02 g ÷ 194.19 g.mol⁻¹
Moles = 1.0 × 10⁻⁴ mol
Calculate Moles of Ethanol as,
As we know one mole of any substance contains 6.022 × 10²³ particles (atoms, ions, molecules or formula units). This number is also called as Avogadro's Number.
The relation between Moles, Number of Particles and Avogadro's Number is given as,
Number of Moles = Number of Molecules ÷ 6.022 × 10²³
Putting values,
Number of Moles = 2.72 × 10²¹ Molecules ÷ 6.022 × 10²³
Number of Moles = 4.5 × 10⁻³ Moles
Explanation:
Given parameters:
Density of silver = 10.5g/cm³
Volume of silver given = 4mL
Unknown:
Mass of silver = ?
Solution:
Density of a substance can be expressed as its mass per unit volume
Density =
we need to convert our volume to cm³ from mL;
1cm³ = 1mL
So 4mL = 4cm³
input the values in;
Mass = density x volume = 10.5 x 4 = 42g
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Answer:
1. Kelvin
Explanation:
The standard temperature for scientific report is the kelvin.
According to the SI unit definition, temperatures should reported in Kelvin.
- On the kelvin scale, the freezing point of water is 273k
- The melting point of water is 373k
- The kelvin is widely accepted in scientific climes.
- It is possible to convert from this scale to another.
Answer:
The partial pressure of Ar is 356.04 torr (=356.04 mmHg)
Explanation:
Step 1: Data given
A mixture of three gases has a total pressure of 1,380 Torr at 298 K.
Moles of CO2 = 1.27 mol
Moles of CO = 3.04 mol
Moles of Ar = 1.50 Ar
Step 2: Calculate total number of moles
Total number of moles = Moles of CO2 + Moles of CO + Moles of Ar = 1.27 + 3.04 + 1.50 = 5.81 moles
Step 3: Calculate mol fraction Ar
Mol fraction Ar = 1.50/5.81 = 0.258
Step 4: Calculate partial pressure
1380 torr * 0.258 moles Ar = 356.04 torr = 356.04 mmHg
The partial pressure of Ar is 356.04 torr (=356.04 mmHg)
Answer:
They are both electropositive
Explanation:
Sodium and Calcium are both metals and therefore they are electropositive.
Both of them have large atomic radius and are willing to lose electrons instead of gaining or sharing of electrons.
To attain stability, both sodium and calcium must lose electrons. So there is no attraction between them to form bonds.