A precipitate is a product of a reaction that is insoluble in the reaction medium (usually water).
Why?
One of the signs that a reaction happened is that a precipitate forms. Let's take the reaction between Silver Nitrate (AgNO₃) and Sodium Chloride (NaCl) as an example:
AgNO₃(aq) + NaCl(aq) → AgCl(s)↓ + NaNO₃(aq)
In this reaction, Silver Chloride (AgCl) is an insoluble product of the reaction, and precipitates out of the reaction medium
If we write down the ionic equation, we find out the following:
Ag⁺ + NO₃⁻ + Na⁺ + Cl⁻ → AgCl(s) + Na⁺ + NO₃⁻
The ions that appear at both sides of the arrow are called spectator ions, since they are not directly involved in the process of the reaction, making the net ionic equation to be:
Ag⁺ + NO₃⁻ → AgCl(s)
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Answer:
D
Explanation:
The amount of energy released or absorbed is equal the product of the mass, the specific heat capacity and the temperature change. The temperature change being the difference between the final and initial temperature.
Q = mc∆T
Q = heat energy (Joules, J) m = mass of a substance (kg) c = specific heat (units J/g∙K)
∆ is a symbol meaning "the change in" ∆T = change in temperature (Kelvins, K)
From the data provided in the question, we can deduce that:
Q = 16.7KJ = 16,700J
m = 225g
c = 1.74J/g.k
For the temperature, let the final temperature be f. This means our ∆T = f - 20
16,700 = 225 * 1.74 * (f - 20)
16700 = 391.5 (f - 20)
f - 20 = 16700/391.5
f - 20 = 42.7
f = 20 + 42.7 = 62.7
Hence the final temperature is 62.7 degrees Celsius
Answer:
There are 8 electrons in the last level. Because of the octet rule.
