# How Do You Convert Molarity to PPM for Calcium Hardness in Pools?

• dagg3r
In summary, errors in calcium hardness can be calculated by multiplying the concentration of Ca2+ (in mmol/L) by the error in the concentration of EDTA (in mmol/L). The error in calcium hardness can be found by multiplying the average titre volume (in cm3) by the error in calcium hardness.
dagg3r
Calucation of ERRORS - CHEM!

hi I am doing one of those determining calcium hardness in swimming pool water here just stuck on a few bits

1) how do i convert concentration (mol/L) -> ppm ( parts per milliion) example i am given concentration of calcium = 8.595*10^-4 M how do i get parts per milliion?

2) i am told to calculate the error in calcium hardness found, all i am given are the error values of concentration EDTA in the burette as 0.01022M and the error 0.00003 M and the average titre volume is 8.41ml with error 0.02 cm^3 what am i meant to do with these errors? and how do i calculate the error in calicum hardness? is it something like this:

1) The conversion folllows directly from the definitions. Concentration is defined as the number of moles of solute per liter of solvent. How amny particles are there in a mole of the solute ? How many in a liter of water ? And what does ppm mean (explain in words, similarly) ?

2) See propagation of errors here : http://www.lhup.edu/~dsimanek/errors.htm
Also, work the examples to make sure you understand. Your text also likely has a chapter right at the beginning, where they talk about error analysis.

Once you know how errors propagate, the first step towards solving your problem is writing the balanced equation for the titration, and calculating the expression for the end point. Then you may apply the techniques for calculating errors.

ok i got the part about the errors that's all fine just the conversion from Molarity (mol/l) to parts per million is confusing.

the concentration of Ca2+ is 8.49*10^04 M how do they go from that to a ppm of Ca2+ 84.900 ?

dagg3r said:
ok i got the part about the errors that's all fine just the conversion from Molarity (mol/l) to parts per million is confusing.

the concentration of Ca2+ is 8.49*10^04 M how do they go from that to a ppm of Ca2+ 84.900 ?
The trick here is to realize that Water Hardness is specified by (ppm CaCO3) and NOT by (ppm Ca+2). However, every Mole Ca+2 in aqueous solution corresponds to 1 original Mole CaCO3. Thus, since "ppm" aqueous solution is equivalent to {mg/(10^6 mg water)}={mg/(10^3 grams water)}={mg/(liter water)}:
{CaCO3 Concentration (moles/lit)} {Ca+2 Concentration (moles/lit)}
{ppm CaCO3} = { CaCO3 Concentration (moles/lit)}*{(100 grams)/(Mole CaCO3)}*{1000 mg/gram} =
= {8.49*10^(-4) M}*{100}*{1000} =
= (84.9 ppm)

~~

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## 1. What are the sources of error in chemical calculations?

The most common sources of error in chemical calculations include human error, instrument error, environmental conditions, and incomplete or inaccurate data. Human error can occur during the measurement or recording of data, while instrument error can be caused by malfunctioning or improperly calibrated equipment. Environmental conditions, such as temperature and pressure, can also affect the accuracy of calculations. Finally, using incomplete or inaccurate data can lead to errors in chemical calculations.

## 2. How can errors be minimized in chemical calculations?

To minimize errors in chemical calculations, it is important to use reliable and calibrated instruments, follow proper measurement techniques, and gather accurate and complete data. Additionally, performing multiple trials and taking the average of the results can help reduce random errors. Double-checking calculations and verifying the units and significant figures can also help minimize errors.

## 3. What is the difference between random and systematic errors in chemical calculations?

Random errors are caused by chance and can occur in any direction, leading to both overestimation and underestimation of results. Systematic errors, on the other hand, are consistent and repeatable and can lead to consistently higher or lower results. Random errors can be reduced by repeating trials, while systematic errors require identifying and correcting the underlying cause.

## 4. How do uncertainties affect the accuracy of chemical calculations?

Uncertainties, or the range of possible values for a measurement, can affect the accuracy of chemical calculations by introducing potential errors. The larger the uncertainty, the less precise the measurement and the higher the chance of error. It is important to consider uncertainties and use appropriate significant figures in calculations to ensure accurate results.

## 5. Can errors in chemical calculations be completely eliminated?

No, it is impossible to completely eliminate errors in chemical calculations. However, by using proper techniques and equipment, and being careful with data and measurements, errors can be minimized. It is important to also acknowledge and account for any remaining uncertainties in the final results.

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