Salvaging mis-measured solutions. Adjusting mass &/or volume to still get the desired concentration

You can probably salvage that solution! How to adjust mass and/or volume to match what you have to still get the concentration you want.
Too much mass? Calculate volume
Measured mass/X = desired concentration
X = measured mass/desired concentration
Needed additional volume = X - current volume
Too much volume? Calculate mass
X/current volume = desired concentration
X = desired concentration x current volume
Extra mass needed = X - current mass
Alternatively, calculate the mass you need to add directly (rather than first finding total then subtracting).
To do that…
Extra volume = current volume - intended volume
Extra mass needed = extra volume x desired concentration
If adding that mass will not appreciably change the final volume, just add it.
If adding that mass would change the final volume, calculate mass for a higher volume with enough wiggle room. Add the mass for that, then adjust the volume to that higher volume.
more on metric conversions: blog: bit.ly/metric_... ; KZbin: • Metric conversions & s...   
 
more on sig figs (which I ignored in this video) here: bit.ly/signific... & • Figuring out sig figs ...   
  
more on dimensional analysis: bit.ly/dimensio... & • Dimensional analysis (...   
  
more about concentrations: bit.ly/sciences... ; KZbin: • Concentration - ways t... & • Working with relative ...    
  
and a couple cheat sheets for molecular weights: drive.google.c...    
  
and concentrations: drive.google.c...     
 
more lab-mathy things: thebumblingbio... & www.youtube.co...
More on the ethanol solution making blog: bit.ly/ethanol... KZbin: • Making 70% ethanol sol...
And solution making in general: blog: bit.ly/ethanol... KZbin: • Making 70% ethanol sol...
 
more about all sorts of things: #365DaysOfScience All (with topics listed) 👉 bit.ly/2OllAB0 or search blog: thebumblingbioc...

[@joshualeft]

This was so useful and well explained!

[@thebumblingbiochemist]

Thanks! So glad you found it helpful. The more I work with students the more I realize there are these little things you get so used to over time but people don't often take time to explain.