Determining the accuracy of varieties of pipettes by weighing and finding the density of a liquid

Abstract
Different varieties of pipettes (P100, PR1000 pipettors and a serological pipette) along with a weighing balance was used in this investigation to check the density of an unknown liquid by first finding out what the liquid weighed and plotting a graph of the mass in grams against the volume of the liquid used in micro litres (µl) and finding the gradient of the graph (∆Y/∆X). Most of the standard deviation values were small showing that they were very close to the mean (average) hence more precise readings were obtained. The results from the graph also showed that the density of the unknown liquid A and B was denser that water and that is because it contains other dissolved substances which increased the overall weight.

Introduction
Pipetting requires a lot of skill to acquire precision and accuracy. For example the pipette tip must be pre-wet about three times before it is dipped into the solution [1] because dry and pre-wet pipette tips reveal greatest discrepancies. Dry pipette tips consistently deliver significantly lower volumes than did the pre-wet tips [2-6]. This can influence the readings showing on the balance as lower volumes will record lower mass and higher volume will record a higher mass which will in turn affect the density which will be measured making the results of the investigation incorrect. Using the right pipette for the right volume increases its accuracy for example using a PR1000 to pipette out 50 µl of a solution will be less accurate than using a P100 to pipette out 50 µl of a solution.

Methodology
Apparatus: P100 pipettor, PR1000 pipettor, serological pipette, pipette aid, weighing balance, weighing boat, sample solutions (pure water and an unknown solution).

Procedure
The serological pipette sucks liquid via the pipette aid. It was first used alongside the PR1000 set to a 100 to pipette out 1000 µl volume of...

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Experiment
Density, Accuracy, Precision And Graphing
OBJECTIVES
1. The determination of the density of water
2. A comparison of the accuracy and precision of a graduated cylinder and a pipet
EXPERIMENTAL MATERIALS
Part A
A 50mL graduated cylinder
A balance
50.0mL deionized water
A rubber policeman
Part B
A 100mL beaker
A 50mL graduated cylinder
A volumetric pipet...

...Pipetting, weighing, accuracy and plotting
Introduction
The aim of this experiment was to determine the density of water and, of unknown solutions, by being as accurate as possible, by pipetting and weighing the solutions.
Density if defined as “The mass per unit volume of substance; common unitg cm-3” (Lewis. R and Evans. W., 2011). As the density is an intensive property of all matter it depends on...

...Pipetting, weighing, accuracy and plotting
Introduction
In this practical, there were three parts in which basic skills and key ideas were put into practice as they are essential to working in the laboratory in order to get reliable and valid results; one of the basic skills put into practice was pipetting. This was the main objective for the whole practical, as pipettors are the fundamental tools used to measure liquids in laboratories. Not only...

...DENSITY OF LIQUIDS AND SOLIDS
by
Lab instructor:
Due date:
Results and discussion:
The purpose of the experiment was to determine the densities of the unknown liquid and solid as precisely and accurately as possible in order to identify them.
It was carried out first on distilled water in order to rule out systematic errors.
A 10 mL beaker was placed on a top pan balance and “tared”. The beaker was then removed and 10 mL...

...1: Precision, Accuracy, and Density Measurements
This experience is intended to introduce the proper use of the most used laboratory equipments and glasswear that is come upon in the lab. As well, to determine the mass, volume and density of water by using various types of measuring glasswear, such as beakers, graduated cylinder, pipet, etc... The measurement of the density of water will determine the precision and...

...Matt R
Results & Analysis
Part 1:
1.) To determine the density and composition of a penny it must be first weighed on a scale. Find the average mass of multiple pennies from the same year. After weighing it find the volume by placing the pennies into a 50 ml beaker with 15 ml of water. Note the change in volume to obtain the volume of the pennies, obtain the average volume, and then calculate the density by dividing the mass of the penny by the...

...Lab No.1: density, accuracy and precision
Aim: to determine the relative precision and accuracy of different glassware items by calculating the density of a known substance.
Introduction: the density of a substance is its mass per unit volume. (where P-density, m- mass and v- volume). Different materials usually have different densities and densities vary according to the...

...Lab Report: [LiquidDensity]
Your Name: ______________________________________________________________
1 Purpose of this Lab
What is the goal of this lab? What question are you trying to answer, or what problem are you trying to explain?
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