Answer:
It is prepared small amounts of hydrogen cloride for uses in the lab.
It can be "generated in an HCl generator by dehydrating hydrochloric acid with either sulfuric acid or anhydrous calcium chloride."
Your first step should be to analyse the compound. For example, if the compound is carbon, you know it always has a valence of four, so, if it has a formula C2H4 (ethylene) it obviously has a double bond. There are difficulties here because benzene C6H6 can be considered to have 6 1.5 C-C bonds, being aromatic.
A second step is to look at its structure. Double bonds are traditionally shorter than single bonds; triple bonds shorter still. Covalent bonds do have typical lengths, nevertheless you can still have problems.
<span>A third step is to consider reactivity. For example, if you have a C=C double bond, you can add, say, bromine to it Thus C2H4 gives C2H4Br2, and by adding two bromine atoms you know you have one double bond. Again, benzene becomes an awkward molecule, but because of this, you know benzene does not have double bonds in the traditional sense</span>
The correct answer is:Some substances keep the same molecular structure when they break down, and others do not.
Some substances change their form when they dissolve and some do not. Dissolution can sometimes be regarded as a sort of reaction between a chemical substance and water.
Usually, we can consider dissolution of a substance in water as a sort of chemical reaction for some substances. For instance, an ionic substance interacts with water to form ions. similarly, some salts become hydrolysed in water and give acidic/basic solutions as result of that.
However, some substances do not interact with water upon dissolution. They rather remain as molecular entities because they are not composed of ions.
We can see that some substances keep the same molecular structure when they break down, and others do not keep the same molecular structure when they dissolve hence it is difficult to classify dissolving as a physical or a chemical change.
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Answer:
Indicates the writer's stance on the main idea of a paragraph. The controlling idea appears in the paragraph's topic sentence. ... The final sentence of a paragraph that summarizes the topic sentence using different words. Words and phrases that show how the ideas in sentences and paragraphs are related.
Explanation:
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The 0.05 moles of 
required to make 1 L of solution in which the 
concentration is 0. 15 M.
Calculation,
The Sodium phosphate dissolves as follows:
→ 
To make 1. L of solution in which the 
concentration is 0. 15 M
The morality of = 0.15 M = number of moles / volume in lit
The morality of = 0.15 M = number of moles /1 Lit
number of moles of = 0.15 mole
The mole ratio is 1: 3
It means, the 1 mole of required to form 3 mole of
So, to form 0.15 mole of = 1×0.15 / 3 moles of required.
Hence, number of moles of required = 0.05 moles.
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