Find out the amount of the elements

In summary, the conversation discusses how to compute the number of moles in 27g of water and how to find the gram amounts of each element. One method is to use the reaction equation and treat the elements as inputs into a limited reagent problem, while another method is to calculate the mass of hydrogen and oxygen present in water using the formula. The molar mass is the sum of all the element masses and can be used to determine the grams of hydrogen in a mole of water.
  • #1
Say17
11
1
Homework Statement
From the following list, indicate the condition(s) that will enable you to obtain at least 27 g of water.
Relevant Equations
H2O = 2*1.01 + 16 = 18.02
Hi everyone,

I just don't get it how to compute the following task. First I have to find out many moles are in 27g of Water.

H2O = 2*1.01 + 16 = 18.02

27g/18.02 = 1.5mol but afterwards how do I find each elements gram?

d is the correct answer.

Image 18.06.23 at 14.34.jpeg
 
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  • #2
Many ways to skin that cat.

You can start with the reaction equation and treat a,b,c,d as input into a limited reagent problem.

You can calculate mass of hydrogen and oxygen present in water. That's what the formula tells you:

Say17 said:
H2O = 2*1.01 + 16 = 18.02

This is basically what you need - molar mass is sum of masses of all elements involved. How many grams of hydrogen per mole of water? What if you have 1.5 times the amount?
 
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FAQ: Find out the amount of the elements

What methods are used to determine the amount of elements in a sample?

Several methods can be used to determine the amount of elements in a sample, including mass spectrometry, atomic absorption spectroscopy, inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray fluorescence (XRF), and neutron activation analysis. Each method has its own advantages and is chosen based on the specific requirements of the analysis.

How accurate are these methods in quantifying elements?

The accuracy of these methods can vary, but generally, they are highly accurate when properly calibrated and used under optimal conditions. For instance, mass spectrometry and ICP-OES can achieve detection limits in the parts per billion (ppb) range or lower. The choice of method often depends on the required accuracy and sensitivity for the specific elements being analyzed.

What are the common challenges in elemental analysis?

Common challenges include matrix effects, where other components in the sample interfere with the detection of the target elements, and the need for proper calibration standards. Sample preparation can also be critical, as improper handling can lead to contamination or loss of analytes. Additionally, some methods require expensive equipment and highly trained personnel.

Can elemental analysis be performed on any type of sample?

Elemental analysis can be performed on a wide variety of sample types, including solids, liquids, and gases. However, the sample preparation and the choice of analytical method may vary depending on the sample matrix. For example, solid samples might need to be dissolved or digested, while gaseous samples might require trapping and concentration before analysis.

How long does it typically take to determine the amount of elements in a sample?

The time required for elemental analysis can vary depending on the method used and the complexity of the sample. Some techniques, such as XRF, can provide results in a matter of minutes, while others, like mass spectrometry, may take longer due to the need for extensive sample preparation and calibration. On average, a complete analysis might take anywhere from a few hours to a couple of days.

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