Don't make these 8 common mistakes in your HSC or HSC Trial exams.
Read the 8 Common Mistakes Chemistry Students Make in the HSC Exam. Learn the errors HSC students are making and avoid them.
2HCl_{(aq)} + Na_{2}CO_{3(s) }→_{ }2NaCl_{(aq) + }CO_{2(g) + }H_{2}O_{(l)}
YEAR 12 CHEMISTRY STUDENTS ARE REQUIRED TO MEMORISE THE SOLUBILITY RULES.
The final answer of all calculation questions must contain the correct number of significant figures. Remember: You are only as accurate as your least accurate value!
To calculate the number of significant figures for HSC Chemistry, use these rules:
Value | Notation |
Mass | m(NaCl) |
Molar mass | MM(NaCl) |
Moles | n(NaCl) |
Volume | V(NaCl) |
Concentration | c(NaCl) |
Question:
Calculate the mass of NaCl required to form a 250.0 mL solution with a concentration of 2.00 mol L^{-1}.
Answer:
n(NaCl) = c(NaCl) x V(NaCl) = 2.00 mol L-1 x 0.250 L = 0.500 mol
m(NaCl) = n(NaCl) x MM(NaCl) = 0.500 mol x 58.44 g mol-1 = 29.2 g (3 sig figs)
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