---
title: "A student performs an experiment to determine the molar mass of an unknown volatile liquid using the Dumas method. A small sample of the liquid is placed in a flask covered with aluminum foil containing a pinhole. The flask is heated in an oil bath until the liquid completely vaporizes and fills the flask, expelling excess vapor. The flask is then cooled, and the mass of the condensed vapor is measured. The student records the data in the table below.  | Measurement | Value | | :— | :— | | Mass of empty flask and foil cap | \\(124.32\\text{ g}\\) | | Mass of flask, foil cap, and condensed liquid | \\(125.20\\text{ g}\\) | | Temperature of heating bath | \\(127^\\circ\\text{C}\\) (\\(400.\\text{ K}\\)) | | Barometric pressure | \\(0.820\\text{ atm}\\) | | Volume of flask | \\(400.\\text{ mL}\\) |  Based on these experimental data, what is the molar mass of the unknown liquid?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/119685/"
date_modified: "2026-08-21T08:12:03+00:00"
---

# A student performs an experiment to determine the molar mass of an unknown volatile liquid using the Dumas method. A small sample of the liquid is placed in a flask covered with aluminum foil containing a pinhole. The flask is heated in an oil bath until the liquid completely vaporizes and fills the flask, expelling excess vapor. The flask is then cooled, and the mass of the condensed vapor is measured. The student records the data in the table below.

| Measurement | Value |
| :— | :— |
| Mass of empty flask and foil cap | \(124.32\text{ g}\) |
| Mass of flask, foil cap, and condensed liquid | \(125.20\text{ g}\) |
| Temperature of heating bath | \(127^\circ\text{C}\) (\(400.\text{ K}\)) |
| Barometric pressure | \(0.820\text{ atm}\) |
| Volume of flask | \(400.\text{ mL}\) |

Based on these experimental data, what is the molar mass of the unknown liquid?

A student performs an experiment to determine the molar mass of an unknown volatile liquid using the Dumas method. A small sample of the liquid is placed in a flask covered with aluminum foil containing a pinhole. The flask is heated in an oil bath until the liquid completely vaporizes and fills the flask, expelling excess vapor. The flask is then cooled, and the mass of the condensed vapor is measured. The student records the data in the table below.

| Measurement | Value |
| :--- | :--- |
| Mass of empty flask and foil cap | \(124.32\text{ g}\) |
| Mass of flask, foil cap, and condensed liquid | \(125.20\text{ g}\) |
| Temperature of heating bath | \(127^\circ\text{C}\) (\(400.\text{ K}\)) |
| Barometric pressure | \(0.820\text{ atm}\) |
| Volume of flask | \(400.\text{ mL}\) |

Based on these experimental data, what is the molar mass of the unknown liquid?

- **A.** \(44\text{ g/mol}\)
- **B.** \(66\text{ g/mol}\)
- **C.** \(72\text{ g/mol}\)
- **D.** \(88\text{ g/mol}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119685/*