Answer:
44 g oxygen are needed.
Explanation:
Given data:
Mass of oxygen needed = ?
Mass of ammonia = 18.2 g
Solution:
Chemical equation:
4NH₃ + 5O₂ → 4NO + 6H₂O
Now we will calculate the number of moles of ammonia:
Number of moles = mass/molar mass
Number of moles = 18.2 g/ 17 g/mol
Number of moles = 1.1 mol
Now we will compare the moles of ammonia with oxygen from balance chemical equation.
NH₃ : O₂
4 : 5
1.1 : 5/4×1.1 = 1.375 mol
Mass of oxygen needed:
Mass = number of moles × molar mass
Mass = 1.375 mol × 32 g/mol
Mass = 44 g
This problem could be solved easily using the Henderson-Hasselbach equation used for preparing buffer solutions. The equation is written below:
pH = pKa + log[(salt/acid]
Where salt represents the molarity of salt (sodium lactate), while acid is the molarity of acid (lactic acid).
Moles of salt = 1 mol/L * 25 mL * 1 L/1000 mL = 0.025 moles salt
Moles of acid = 1 mol/L* 60 mL * 1 L/1000 mL = 0.06 moles acid
Total Volume = (25 mL + 60 mL)*(1 L/1000 mL) = 0.085 L
Molarity of salt = 0.025 mol/0.085 L = 0.29412 M
Molarity of acid = 0.06 mol/0.085 L = 0.70588 M
Thus,
pH = 3.86 + log(0.29412/0.70588)
pH = 3.48
Answer:
average for silk =141"
average for cotton =96"
average for nylon = 70"
if you desire a slower falling parachute to protect the body from damage,
silk is the best
if you desire a faster falling parachute to escape enemy bullets,
nylon is the best
Explanation:
Homework 1
Problem Solving
1. Kelvin and Xavier were doing an investigation on parachutes. One of them suggested that the type of material the parachute was made from had an effect on how long it took to reach the ground. Their results are given in
the table below.
(a) Calculate the average time in seconds for each material.
Time taken for parachute to reach the ground (seconds)
MATERIAL
1st TRY
2nd TRY
3rd TRY
AVERAGE
Sik
144
140 average of 3 = 141
139
Cotton
98
96 average of 3 = 96
94
Nylon
72
68 average of 3 = 70
70
There is only one product in a synthesis reaction.
