# Convention for writing concentration units

1st part of my question:

Q) The concentration of an NaCl solution is 1M. Express this in percent wt. by vol. unit.

Ans:

$$\text{In %(w/v) unit}=\frac{58.5\pu g}{1000\pu{mL}}\times \frac{100}{100}=5.85\ \pu{\%(w/v)}\tag{1}$$

$$\text{In (w/v)% unit}=\frac{58.5\pu g}{1000\pu{mL}}\times \frac{100}{100}=5.85\ \pu{\%(w/v)}\tag{2}$$

2nd part of my question:

Q) The concentration of an NaCl solution is 1M. Express this in ppm unit.

Ans:

$$\text{In ppm(w/v) unit}=\frac{58500\pu{mg}}{1\pu{L}}=58500\ \pu{ppm}\tag{3}$$

$$\text{In (w/v)ppm unit}=\frac{58500\pu{mg}}{1\pu{L}}=58500\ \pu{ppm}\tag{4}$$

My questions:

1. Which of $$(1)$$ and $$(2)$$ is correct?
2. Also, the unit of molarity is $$\pu M$$, or the unit of mass is $$\pu {kg}$$. Similarly, what is the unit in the first part of my question? Is it $$\text{%(w/v)}$$? Is $$\text{%(w/v)}$$ a unit just like $$\pu{kg}$$ and $$\pu{M}$$?
3. Which of $$(3)$$ and $$(4)$$ is correct?
4. Also, is it okay if I append/suffix (w/v) at the end of ppm? For example, if I say the concentration of NaCl is $$58500\ \pu{ppm(w/v)}$$ instead of saying that the concentration of NaCl is $$58500\ \pu{ppm}$$, will it be okay?
• By not explicitly presenting own attempts to answer it, you put the question in closing danger. May 8, 2022 at 13:50

• Thank you so much for your answer! Also, could you please tell me which of the statements $(1)$ and $(2)$ seem more correct to you? May 11, 2022 at 4:47
• Understood. Also, should I write $$\text{In % w/v unit}=\frac{58.5\pu g}{1000\pu{mL}}\times \frac{100}{100}=5.85\ \pu{\% w/v}\tag{1}$$ or $$\text{In w/v % unit}=\frac{58.5\pu g}{1000\pu{mL}}\times \frac{100}{100}=5.85\ \pu{\% w/v}\tag{2}$$ May 11, 2022 at 5:39