A physical change<span> in a substance doesn't </span>change<span> what the substance is. In a </span>chemical change<span> where there is a </span>chemical reaction<span>, a new substance is formed and energy is either given off or absorbed.</span>
Answer:
1 x 10^-12 mol dm^-3
Explanation:
[H+] = 10 ^ -pH
Therefore, pH 12 = 1 x 10^-12 hydrogen ion concentration
Answer:
3.14 grams of ammonium thiocyanate must be used to react completely with 6.5 g barium hydroxide octahydrate.
Explanation:

The balance chemical equation is :

Mass of barium hydroxide octahydrate = 6.5 g
Moles of barium hydroxide octahydrate = 
According to reaction, 2 moles of ammonium thiocyanate reacts with1 mole of barium hydroxide octahydrate. The 0.020635 moles of barium hydroxide octahydrate will react with:

Mass of 0.04127 moles of ammonium thiocyanate;

3.14 grams of ammonium thiocyanate must be used to react completely with 6.5 g barium hydroxide octahydrate
Answer:
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