Answer:
Explanation:
1) Given data:
Number of moles of lead = 4.3×10⁻³ mol
Mass of lead = ?
Solution:
Mass = number of moles × molar mass
Molar mass of lead = 207.2 g/mol
Mass = 4.3×10⁻³ mol × 207.2 g/mol
Mass = 890.96 g
2) Given data:
Number of atoms of antimony = 3.8×10²² atoms
Mass of antimony = ?
Solution:
1 mole contain 6.022 ×10²³ atoms
3.8×10²² atoms × 1 mol / 6.022 ×10²³ atoms
0.63×10⁻¹ mol
0.063 mol
Mass = number of moles × molar mass
Molar mass of lead = 121.76 g/mol
Mass = 0.063 mol × 121.76 g/mol
Mass = 7.67 g
3) Given data:
Mass of tungsten = 15.5 Kg (15.5 kg × 1000 g/ 1kg = 15500 g)
Number of atoms = ?
Solution:
Number of moles of tungsten:
Number of moles = mass/molar mass
Number of moles = 15500 g / 183.84 g/mol
Number of moles = 84.3 mol
1 mole contain 6.022 ×10²³ atoms
84.3 mol × 6.022 ×10²³ atoms / 1mol
507.65 ×10²³ atoms
Answer:
4Na + O₂ → 2Na₂O
6.82g
Explanation:
The combustion of sodium involves combining the element with oxygen gas:
4Na + O₂ → 2Na₂O
We have been given 5g of Na.
The balanced reaction equation is given as shown above. This reaction is also a synthesis or combination reaction.
b. Maximum amount of product that can be obtained.
Sodium is the limiting reactant and it will determine the amount of product that can be formed.
To solve this, we find the number of moles of the given sodium.
Mass of given sodium = 5g
Molar mass of Na = 23g/mol
Number of moles of Na =
Insert the parameters and solve;
Number of moles of Na = = 0.217moles
From the balanced reaction equation:
4 moles of Na will produce 2 moles of Na₂O
0.217 moles of Na will produce = 0.11mole of Na₂O
So;
Mass of Na₂O = number of moles x molar mass
Molar mass of Na₂O = 2(23) + 16 = 62g/mol
Mass of Na₂O = 0.11 x 62 = 6.82g
Answer:
Explanation:
To calculate the moles, we use the equation:
According to stoichiometry :
2 moles of releases = 6542 kJ of heat
0.9858 moles of release = of heat
Thus heat given off by burning 7.700 g of will be absorbed by water.
Q = Heat absorbed= 3224kJ = 3224000J (1kJ=1000J)
m= mass of water = 5691 g
c = specific heat capacity =
Initial temperature of the water = = 21.0°C
Final temperature of the water = = ?
Putting in the values, we get:
The final temperature of the water is
=58.464 kg/hr
width= 21.0 feet
length= 20.0 feet
snowflake mass=1.60 milligrams
1 foot^2=1450 snowflakes per minute
area of lawn=length*width
area=(21.0)(20.0)
area=420 feet^2
1450 snowflakes at 1.60 milligrams per snowflake:
(1.60)(1450)=2320 milligrams
2320 milligrams to kilograms:
=(2320 mg)(1 gram/1000 mg)(1 kilogram/1000 grams)
=(2320)(1/1000)(1/1000)
=(2.32)(1/1000)
=0.00232 kg per minute
0.00232 kg per minute to kg per hour:
=(0.00232 kg/1 minute)(60 minutes/1 hour)
=(0.00232)(60)
=0.1392 kg per hour per square foot
For the total lawn's accumulation in kilograms per hour, multiply by area:
=(0.1392 (kg/hr) per 1 foot^2)(420 feet^2)
=58.464 kilograms of snow accumulate on the lawn per hour
Answer:
C₈H₈O₃
Explanation:
The empirical formula is the simplest whole-number ratio of atoms in a compound.
The ratio of atoms is the same as the ratio of moles.
So, our job is to calculate the molar ratio of C:H:O.
Assume 100 g of the compound.
1. Calculate the mass of each element.
Then we have 63.15 g C, 5.30 g H, and 31.55 g O.
2. Calculate the moles of each element
3. Calculate the molar ratio of the elements
Divide each number by the smallest number of moles
C:H:O = 5.258:5.258:1.972 = 2.667:2.666:1
4. Multiply by a number to make each ratio close to an integer
Multiply the ratios by three.
2.667:2.666:1 = 8.000:8.000:3 ≈ 8:8:3
5. Write the empirical formula
EF = C₈H₈O₃