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Chemistry Regents January 2008 - Question 77 |
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Written by The Chemistry Wizard
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.jpg) (12g/mol) / (106 g/mol) x 100
(molar mass of carbon is 12 g/mol) (molar mass of Na2CO3 is 106 g/mol)
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Chemistry Regents January 2008 - Question 78 |
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Written by The Chemistry Wizard
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This is an endothermic reaction because heat is consumed in this process. It is also a
decomposition reaction.
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Last Updated on Friday, 13 March 2009 18:06 |
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Chemistry Regents January 2008 - Question 79 |
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Written by The Chemistry Wizard
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7/2 moles or 3.5 moles.
In order to solve this problem, you need to note the 2:1 ratio for the compounds involved.
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Last Updated on Friday, 13 March 2009 18:07 |
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Chemistry Regents January 2008 - Question 35 |
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Written by The Chemistry Wizard
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(4) 310 g/mol is the correct answer.
In order to calculate gram formula mass, you simply need to count the number of atoms in the compound and refer to the molar masses on your periodic table.
In this compound there are 3 Ca atoms (3 x 40), 2 P atoms (2 x 31), and 8 O atoms (8x16).
120 + 62 + 128 = 310 g/mol.
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Chemistry Regents January 2008 - Question 09 |
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Written by The Chemistry Wizard
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(3) is the correct answer.
In equation 3, there are the same number of atoms on each side of the equation. (Six atoms in the products and six atoms in the reactants.)
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Chemistry Regents January 2008 - Question 13 |
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Written by The Chemistry Wizard
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(3) hexane is the correct answer.
Only hexane is a compound, which means it can be broken down by a chemical change. The other choices are elements, which means that they will not be broken down in a chemical reaction.
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Chemistry Regents January 2008 - Question 15 |
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Written by The Chemistry Wizard
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(3) mol/L is the correct answer.
These are the units for solubility or the concentration of a solution. Concentration is described as how much solid (measured in moles) can be dissolved in a solution.
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Chemistry Regents January 2008 - Question 23 |
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Written by The Chemistry Wizard
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(1) decreases because the concentration of ions decreases is the correct answer.
As water is added to a solution of NaCl, the concentration of ions decreases because the amount of solution increases. Conductivity of a solution is measured by the concentration of free ions, so fewer ions results in a poorer conductor.
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Chemistry Regents January 2008 - Question 34 |
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Written by The Chemistry Wizard
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(4) 310 g/mol is the correct answer.
In order to calculate gram formula mass, you simply need to count the number of atoms in the compound and refer to the molar masses on your periodic table.
In this compound there are 3 Ca atoms (3 x 40), 2 P atoms (2 x 31), and 8 O atoms (8x16).
120 + 62 + 128 = 310 g/mol.
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Chemistry Regents January 2008 - Question 37 |
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Written by The Chemistry Wizard
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(1) calcium bromide is the correct answer.
CaBr2 contains 1 metal ion (calcium) and 2 non-metals (bromine).
In this case, calcium bromide is the only compound option that contains 3 atoms in total so it is the most reasonable option.
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