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: https://bit.ly/metric_calcs ; YouTube:    • Metric conversions & scientific notat...     
 
more on sig figs (which I ignored in this video) here: http://bit.ly/significantfiguress &    • Figuring out sig figs - working with ...     
  
more on dimensional analysis: http://bit.ly/dimensionalanalysising &    • Dimensional analysis (aka factor-labe...    
  
more about concentrations: http://bit.ly/sciencestocksolutions ; YouTube:    • Concentration - ways to report it (mo...   &    • Working with relative concentrations ...     
  
and a couple cheat sheets for molecular weights: https://drive.google.com/file/d/1TqCR...    
  
and concentrations: https://drive.google.com/file/d/1v7pf...     
 
more lab-mathy things: https://thebumblingbiochemist.com/let... & https://www.youtube.com/playlist?list...

More on the ethanol solution making blog: https://bit.ly/ethanol_solution; YouTube:    • Making 70% ethanol solutions (the rig...  

And solution making in general: blog: https://bit.ly/ethanol_solution; YouTube:    • Making 70% ethanol solutions (the rig...  
 
more about all sorts of things: #365DaysOfScience All (with topics listed) 👉 http://bit.ly/2OllAB0 or search blog: http://thebumblingbiochemist.com