What are some common challenges faced in chemistry problem solving?

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Discussion Overview

The discussion revolves around common challenges faced in solving chemistry problems, particularly focusing on stoichiometry, chemical reactions, and calculations involving moles and mass. Participants seek assistance with specific homework problems related to these topics.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • Post 1 presents several chemistry problems, including calculations for molar mass, percentage composition, and stoichiometric relationships in chemical reactions.
  • Post 2 emphasizes the importance of showing work and reasoning to facilitate assistance, indicating that participants should engage in problem-solving rather than seeking direct answers.
  • Post 3 points out that the particle masses provided in the first question are incorrect, suggesting that this may affect the calculations.
  • Post 4 shares progress on some problems but indicates a lack of complete working out, particularly regarding the ratios and molar masses needed for calculations.
  • Post 4 also mentions confusion about using the ideal gas law (PV=nRT) for one of the problems, highlighting the challenges in applying theoretical concepts to practical problems.

Areas of Agreement / Disagreement

Participants generally agree on the need for showing work and reasoning in problem-solving. However, there is no consensus on the specific approaches to solving the problems presented, and several participants express uncertainty about their calculations and methods.

Contextual Notes

Some participants express uncertainty about the correctness of their calculations and the balancing of chemical equations. There are also references to missing information, such as molar masses and the ratios in chemical reactions, which may affect the ability to solve the problems accurately.

Who May Find This Useful

Students encountering difficulties in chemistry problem-solving, particularly in stoichiometry and chemical reactions, may find this discussion helpful.

dude_007
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a) Calculate the expected mass of one mole of 31^P atoms that the avogadro constant equals 6.0225 x10^23, the mass of one electron equals 9.1091x10^-28g, the mass of one proton equals 1.6725x10^-24g and the mass of one nuetron equals 1.6748x10^-24g.

b) The actual mass of one mole of 31^P atoms is 30.9738g. Try to account for the difference between this valueand your answer in (a).

3.
A mixture of MGS04 and CuSO4.7H20 is heated at 120(degrees C) until a mixture of the anhydrous compounds is produced. If 5.00g of the mixture gave 3.00g of the anhydrous compounds, calculate the percentage by mass of MGSO4.7H20 in the mixture.

4.
1 mole of a hydrocarbon formula CnH2n was burned completely in oxygen producing carbon dioxide and water vapour only. It requires 192g of oxygen. Work out the formula of the hydrocarbon.

5. When 15cm^3 of gaseous hydrocarbon was exploded with 60cm^3 of oxygen (an XS), the final volume was 45cm^3. This decreased by 15cm^3 on treatment with NaOH solution ( removes C02 ). What was the formula of the hydrocarbon (all measuremnets were made at room temp. and pressure, & water produced is liquid)

6.
A fertilser contains ammonuim sulphate and pottasuim sulphate. A samply of 1.455g of the fertilise was warmed with 25cm^3, 0.2moddm^-3 NaOH solution giving of ammonia gas. The remaining NaOH that was not used requireed 28.7cm^3 of 0.100moldm^-3 HCl acid for nuetrulisation. Calculate the % by mass of ammonuim sulphate in the sample


I HAVE NO IDEA HOW TO DO ANY OF THESE PLEASE HELP ME I HAVE UNTIL FRIDAY
 
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Can you show of the work/thinking/reasonning you have done on these problems. People will point out the errors and they help you solve your problem.

We are here to help but we are not here to do your homework.
 
Hint; in the first question all three particle masses are incorrect, some by small amount, some large.

The others; you have some digging to do.
 
sorry i now done 2ab and no. 5


3-
no real working outs because all i cud figure out that 2g of water had been extracted.

6-
I "think" its all a 1-1 ratio equation, so i found out moles of NaOH but then couldn't find mass because i don't no a; if the equation is balance b;the Mr of the ammonuim sulphate.


5-
I tried to use the pv=nrt forumula to work out the amount of moles used, after that i was lost on wat to do
 

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