[Da4gotten]

A set of five solutions are prepared by delivering 10 mL of unknown sample and increasing
volumes of standard (0, 5, 10, 15, and 20 mL) into 50-mL volumetric flasks. Analytical
reagents are then added and diluted to volume. The x-intercept is –3.90 mM. What is the
unknown concentration?

[billnotgatez]

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[Arkcon]

A graph would help you visualize the answer, but there is a formula you should have been given that would give you the answer.

[Da4gotten]

I tried constructing a graph, but I was a bit confused on how to start.

It's fairly easy to construct a graph, but since I don't have the initial concentration of the solution I don't even know how to plot the first point (when y= 0).

The only formula I can think of that might solve this problem would be: concentration of unknown = -(x-intercept X concentration of standard0/ Total volume.

And I'm not even sure it's that one.