wunder beta🧪 How Serial Dilution Works
1.0 milliliter into 9.0 milliliters. Mix. That tube is one-tenth the last, and the next tube is one-tenth of this one — a chain, not a single heroic pipette.
What you’ll learn
- Name the ratioName a 1:10 step as 1 volume plus 9, and separate the concentration fraction from the dilution factor.The same tenfold mix is 1+9, 10+90, or 100+900. Serial exists so each step stays measurable.
- Run the chainLabel first, fill a compatible diluent, transfer with a fresh pipet, and mix before the tube becomes the next source.A serial dilution is a chain with memory. Mixing and identity are part of every step.
- Read the countMultiply step factors, walk a plate count back to the stock, and treat 30–300 as a teaching window rather than a single law.The plate is a countable window. The factor and the plated volume put the number back on the stock.
Questions this course answers
In the OpenStax and BAM convention, what is a 1:10 dilution step?
OpenStax: 1.0 mL into 9.0 mL of sterile broth is a dilution factor of 10, or 1:10. BAM uses 10 mL into 90 mL. Adding 1 plus 10 is an elevenfold mix.
Roth Lab labels the undiluted stock as 10⁰. What is the first tenfold tube?
Roth: typical dilutions are 10-fold; the first 10-fold dilution is termed the 10⁻¹ dilution. Each later tube is made from the previous one.
Put the wet work in a useful order.
BPS: label, add diluent, transfer stock, mix, then repeat with a fresh tip. Mixing is part of the step, not a flourish after the rack is done.
Why must a dilution tube be mixed before it is used as the next source?
OpenStax: thorough mixing so the cell distribution is random is paramount. BAM shakes food bottles 25 times in a 30 cm arc within 7 seconds, and again if they sit more than 3 minutes. Incomplete mixing is not a local stain.
OpenStax counts 50 colonies from a 1:10,000 dilution, with 0.1 mL plated. What is the stock in CFU/mL?
50 × 10 (because only 0.1 mL was plated) × 10,000 = 5,000,000 CFU/mL. The plate is a countable window onto a diluted sample, not the stock itself.
What is the total dilution after three consecutive 1:10 steps?
0.1 × 0.1 × 0.1 = 0.001, or 10 × 10 × 10 = 1,000. OpenStax: the second mix is already 1:100 versus the original; the third is 1:1,000.
Grounded in trusted sources
- [object Object]
- [object Object]
- [object Object]
- [object Object]
- [object Object]
- [object Object]
Every Wunder lesson is built from real, reputable sources — never invented.
Related Science courses
Wunder is a personalized learn-anything platform — tell it any topic and it builds a beautiful, fact-checked course in minutes, with narration, a knowledge check, and a college-style University track.
Browse more Science courses · All topics · Home
© 2026 Wunder Learning LLC · Terms & Privacy