I need help with some chemistry problems?

pisgahchemist

Standard deviation .... The equation shown below is for the sample standard deviation where you divide by (n-1). The population standard deviation (divide by n, rather than n-1) is seldom used in chemistry because it is used when there are no other possible measurements. Start by finding the arithmetic mean, x̄ of the n measurements. The subtract the measurements to get the "residuals." Square the residuals and get their sum. Divide by n-1. Lastly take the square root. The standard deviation gives you a measure of the "spread" in your data and is related to the number of significant digits in the answer. This is all about precision, not accuracy. Accuracy is how close to the "correct" answer you are. Precision is about the reproducibility of the data. The more reproducible, the less the spread and the lower the value of the standard deviation. A low standard deviation means a high precision. .