An indicator shows where the endpoint of a titration is. Different indicators will change colors at different equivalence points. Phenolphthalein will change colors at around pH7.5 or so, and others like Methylene Blue will change around a pH of 6. Different titrations will have different pH's at different equivalence points.
Answer:
20.95 g of caffeine, C₈H₁₀N₄O₂
Explanation:
From the question given above, the following data were obtained:
Number of molecules of C₈H₁₀N₄O₂ = 6.5×10²² molecules
Mass of C₈H₁₀N₄O₂ =?
From Avogadro's hypothesis,
1 mole of C₈H₁₀N₄O₂ = 6.02×10²³ molecules
Next, we shall determine the mass of 1 mole of C₈H₁₀N₄O₂. This can be obtained as follow:
1 mole of C₈H₁₀N₄O₂ = (8×12) + (10×1) + (4×14) + (2×16)
= 96 + 10 + 56 + 32
1 mole of C₈H₁₀N₄O₂ = 194 g
Thus,
194 g of C₈H₁₀N₄O₂ = 6.02×10²³ molecules
Finally, we shall determine the mass of caffeine, C₈H₁₀N₄O₂ that contains 6.5×10²² molecules. This can be obtained as follow:
6.02×10²³ molecules = 194 g of C₈H₁₀N₄O₂
Therefore,
6.5×10²² molecules = (6.5×10²² × 194) / 6.02×10²³
6.5×10²² molecules = 20.95 g of C₈H₁₀N₄O₂.
Therefore, 20.95 g of caffeine, C₈H₁₀N₄O₂ contains 6.5×10²² molecules
Answer:
m = 0.544 moles/kg
Explanation:
To do this, we need to use the expression for molality of a solution which is:
m = n / kg water
Where:
n: moles of solute
m: molality of solution
In this case, we have the moles of the solute, which is the C6H12O6 and the grams of water, and these grams would have to be turn into kg. Let's do this first:
kg of water = 150 g * 1 kg / 1000 g = 0.150 kg of water.
Now, replacing in the above expression of molality, we can calculate the molality of the solution:
m = 0.0816 / 0.150
<h2>
m = 0.544 moles/kg</h2>
Answer:
can you be more clear with your question :
Answer:
All electromagnetic waves: are transverse waves; can travel through a vacuum ; travel at exactly the same speed in a vacuum, the speed of light, 300,000,000 m/s.
...
Like all waves, electromagnetic waves:
transfer energy from one place to another;
can be reflected;
Explanation:
