The valence level of an atom refers to the number of electrons that reside in the upper most energy level. Nitrogen has an atomic number of 7 and therefore has 7 electrons. The first energy level (1) holds 2 electrons, leaving 5 electrons to reside in the second energy level (2s and 2p). Therefore the valence of nitrogen is 5.
Answer:
5.63 g
Explanation:
Step 1: Write the balanced equation
CuBr₂(aq) + 2 AgCH₃CO₂(aq) ⇒ 2 AgBr(s) + Cu(CH₃CO₂)₂(aq)
Step 2: Calculate the reacting moles of copper (II) bromide
30.0 mL of 0.499 M CuBr₂ react. The reacting moles of CuBr₂ are:

Step 3: Calculate the moles formed of silver (I) bromide
The molar ratio of CuBr₂ to AgBr is 1:2. The moles formed of AgBr are 2/1 × 0.0150 mol = 0.0300 mol.
Step 4: Calculate the mass corresponding to 0.0300 mol of AgBr
The molar mass of AgBr is 187.77 g/mol.

Explanation:
4. limestone heat lime + carbon dioxide
The reactants in this expression above is limestone
The products of the reaction is carbon dioxide and lime
Reactant is the species that gives the product and it is usually found on the left hand side of the expression.
The product is the substance on the right hand side of the expression that forms through the experiment.
Heat is used to facilitate the reaction.
5. An exothermic reaction is a reaction in which heat is given off.
An endothermic reaction is a reaction in which heat is absorbed in the process.
An exothermic reaction is always warmer after the reaction whereas an endothermic reaction is colder at the end of the reaction.
6. Sodium salicylate is made from carbon dioxide and sodium phenoxide.
The reactants are:
Carbon dioxide and sodium phenoxide
The product is:
Sodium salicylate
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