Moles Definition and 202 Threads

Homework Statement A silicon chip used in an integrated circuit of a computer has a mass of 4.86 mg. How many silicon atoms are present in this chip? Homework Equations no. of moles of element = no. of particles / 6.22 * 10^23 particles No. of moles of a element : mass of element...

Dealing with these has reminded me why I hated chemistry. What is the relationship between the above 3? Given atomic weight of nitrogen and Avogadro's constant, can the number of moles be found?

Homework Statement ##300.0 mL## of ##1.50 \times 10^{-10} M## ##Na_2S_{(aq)}## is combined with ##200.0 mL## of ##1.50 \times 10^{-10} M## ##{Co(NO_3)_2}_{(aq)}##. Determine what precipitates. Determine how many moles precipitate. Homework Equations The Attempt at a Solution...

Homework Statement Calculate the number of moles of CO2 that are emitted into the atmosphere per year due to the total energy consumption on Earth (16TW). Note: 1kg oil yields 42MJ and for oil C:H ' 1:2. I don't know how to calculate how many grams/moles of CO2 are emitted by burning 1kg of...

I've been given information that the exhaust gas contains only water and no HydroCarbons. So,the only hydrogen composition found in the exhaust gas is in the water. Similarly,the hydrogen in the air coming-in is only found in the water molecules as the incoming air is pure and without any fuel...

From Statsitical And Thermal Physics (Reif. international edition 1985) 160 page. (5.4.4) S(T,V;√) = √[∫{cv(T`)/T`}dT` + Rln(V) - Rln(√) + constant] (integral is from T0 to T , cv is specific heat) This is a entropy of system for temperature 'T' , Volume 'V' , Moles '√' <--...

Homework Statement Suppose you have 6 moles of H20. You want to calculate how many moles of H2 you have. how many is it? Homework Equations Avagradro's number: 6.02*10^{23} The Attempt at a Solution I got to the equation: 2H_2+O_2\rightarrow 2H_2O I kind of figured out...

[FONT="Arial"]Homework Statement "1.79 g of a fuel was burned in the presence of oxygen. The fuel is a composite of 90% octane and 10% ethanol. Calculate the number of moles of this fuel that was burned."Homework Equations Moles = Mass/Molar Mass The Attempt at a Solution 90% of 1.79 g is 1.61...

If I want to calculate the number of moles ratio of reactants which, in a reversible reaction of equilibrium constant K, will give me a certain yield 'f', what is the mathematical definition of the yield in this case? For instance, in the reaction A + B ⇔ C + D, let's say we can denote extent...

Homework Statement Hi! I was assigned a problem for chemistry like this: 2 A + B → 2 C + 3 D It asks to find mol of C if you start with 0.320 mol D.. Can I convert between C and D? I know that I can convert between A and B.. but I'm not sure about C and D. Homework Equations...

Hi All, I would like to understand a little more about the following equation moles = \frac{Mass(g)}{Molar Mass} I know that this is to calculate the Moles for use in the ideal gas law equation PV=n \times R \times T Lets say I had to find two variable in the ideal gas law...

1. If I have this chemical formula : Mg(NO3)2 and I have one mole of it, how many moles of each element do I have ? Mg: 0,16mol N2: 0,19 mol O6: 0,65 mol Homework Statement Would my answer be any good ?

Hello, I have no idea how to solve this... The initial mass of an unknown sample containing iron (II) is 0.512 g. 12.6 mL of 0.01522 M KMnO4 is required to titrate the unknown to the endpoint. a) How many moles of MnO4- were added? b) How many moles of iron (II) must be present in the...

Homework Statement Estimate the number N of molecules in a few grams of matter. Explain why in that case ln (N) is of the order of 50 whatever the chemical composition. Homework Equations M = m/N where M is the molecular mass The Attempt at a Solution I'm really unsure about the entire...

A group of students decided to use AAS to analyze three different brands of iron tablets to determine their content. They placed a tablet in a 100 mL beaker with 6 mol/L HCl and covered it with a watch glass and heated slowly for 15 min. They then filtered the solution into a 250 mL volumetric...

Homework Statement Fe[3+]+V[2+]-->Fe[2+]+V[3+] If you start with 0.1000 M solutions and the first-named species is the titrant, what will be the concentration of each reactant and product at the equivalence point of the titrations above? Assume that there is no change in [H+] during the...

Homework Statement 2.0 moles of a monatomic gas interacts thermally with 2.0 moles of an elemental solid. The gas pressure decreases by 50 degrees C at constant volume. What is the temperature change in the solid? I missed this day in class and I have no idea where to even begin...

Homework Statement *0.3 L OF 0.005 M Ba(OH)- What is the number of moles of OH- in 0.3 L OF 0.005 M Ba(OH)- ?2. The attempt at a solution In 1 mol ba(oh)2--------> 2 mol OH- so In 0.005 M ba(oh)2 ----------------> 2 x 0.005 M OH- I know I am doing something wrong. please help thanks in...

If someone could check my work on this, I'd appreciate it: Thanks!

Homework Statement We are given a reaction: H2O2 + 2I- + 2H+ → 2H2O + I2 and are asked to find the initial number of moles of each reactant. V=10mL and C=0.2 mol/L for potassium iodide in the solution. V=5mL and C=0.5 mol/L for sulfuric acid in the solution. V=5mL and C=0.02 mol/L for...

Homework Statement This is the statement out of a paper: Slurry 10 grams of ZnS with 3mL of .2N Cu(CH3COO)2 solution (corresponding to 0.6 atom % Cu) and 1.7 mL of .2N NH4Cl solution (corresponding to 0.34 atom % Cl) So my question is how did they calculate the .6 at. % and .34 at. %...

Homework Statement The number of moles of valence electrons in 1 mole nitride ions are? Homework Equations Nitride ion- N3- The Attempt at a Solution The number of electrons are 8. Therefore number of moles should also be 8?

Homework Statement What would be the mass of one hundred million million (100 000 000 000 000 = 1014) atoms of Uranium 238 (atomic mass is 238)? Homework Equations The Attempt at a Solution I tried finding the mass of each particle by diving the avogadro constant by 238.. The...

Hi guys, I have been solving many stoichiometry problems but their is something I can do but I don't fully understand why it works it kinda confuses me atleast on mathematical level. I don't like doing something I don't fully understand. What I don't understand is if we have for example a...

[SIZE="4"]Hi, I learned recently Avogadro's principle which states " At constant temperature and pressure, equal volumes will contain the same number of molecules" this can be translated to if you double the volume, you double the number of moles. Now i don't get that at all! where does the...

Can anyone help me with this problem? Find the pH when 45.0 mL of 0.250 M NaOH(aq) is added to 35.0 mL of 0.200 M HCl(aq). I started by converting the molarities into moles but I'm having trouble with what the reaction should look like. Shouldn't it produce a salt (NaCl) and water? And...

Homework Statement Calculate the moles of NaOH in the reaction of NaOH + acetic acid. This is a titration where the NaOH neutralized the acetic acid. It took 0.02 L of NaOH to neutralize 3 ml of acetic acid. I just do not know what to do, have been trying for a few days and can't seem to...

Homework Statement Here is the problem: Carbon monoxide and oxygen are kept at exactly 300 K in separate chambers of the apparatus shown below. When the stopcock is opened, the combustion reaction begins and is allowed to proceed to completion, while being maintained at exactly 300 K...

Homework Statement 10. An ideal gas in a container has a pressure of 2.50 atm and a volume of 1 m3 at a temperature of 30oC. How many moles of gas are in the container? a. 20 moles b. 45 moles c. 62 moles d. 83 moles e. 100 moles Homework Equations PV=nRT The Attempt at a...

Homework Statement Was wondering if I did this right, don't know if I used the right equation. Equation: Ba(NO3)2 + Na2(SO4) = Ba(SO4) + 2Na(NO3) Volume of barium nitrate: 5mL Molarity of Barium nitrate: .1M Homework Equations Molarity = moles/L The Attempt at a Solution...

Homework Statement There is 400 mL of 0.2 M histidine buffer- pH 11. Find the moles of HCl that are needed to change the pH to 3.2. Homework Equations pH= pKa+log[b]/[a] The Attempt at a Solution First, this is how you would go from acid to base (acid-->base): 1. There is 400 mL of 0.2 M...

Homework Statement i have just learned that one mole is actually what i had learned as one molecule. now one atom is also known as one mole.eg. one mole of methane has 5 moles of atoms( this sentence is written by my teacher and no matter how i try to look at it from different perspectives...

Homework Statement I want to find a relationship between the number of moles of O2 used and the number of CH2 units in an alkane in a complete combustion reaction. Homework Equations The Attempt at a Solution Right now I have come up with a math equation, given X units of CH2...

Homework Statement A gas cylinder contains of 0.8 × 10^-3 m^3 volume oxygen.the temperature of the oxygen is 320k,and the pressure of the gas is 1.5 × 10^6 Pa.how to calculate: number of moles and molecules of Oxygen? mass of Oxygen if its molar mass is 32.0 × 10^-3 kg ? The mass of a single...

Homework Statement Calculate the number of moles of oxygen gas produced from the completely catalyzed decomposition of 6.60ml sample of a 3.5% solution of H2O2. The density of the 3.5% solution of H2O2 is 1.01 g/ml. Homework Equations 2(H2O2) --> 2(H2O) + O2 p=m/v The Attempt...

Alright, below are screen captures of some work that I'm tackling. They show my attempts and answers at the problems. I would like to know whether I'm correct or wrong and how to correct the mistakes. The one I need most help with is, the one where you're given density and asked to find...

A diatomic ideal gas is in a rigid container at an initial sate of 300K and 1.3x10^5 Pa is heated to a final state of 330K by 623.25J of heat. calculate the pressure in the container after the heating, the work done by the gas, the change in internal energy and the volume of the container. if...

If I have BaCl2 *2H2O how does that come to 8.46507394x10-3 Here is the question: A common laboratory experiment involves the analysis of a mixture of BaCl2 and BaCl2 *2H2O. you are given a white powder that is a mixture of these compounds and are asked to determine the weight percent of...

Homework Statement What molar concentration of each ion appear in 0.16M Pb(NO3)2? *Note* The title incorrectly says "moles". Homework Equations M = mol/L The Attempt at a Solution My teacher tells me this is wrong, but I can't see my fault: Molar Mass of Pb+2 = 207.20g Molar Mass of NO3-...

Do both of these methods for calculating the number of moles work? we've learned a new method recently which i prefer over the older method for current curriculum n1=c1v1 n for number of moles, c for concentration 1 and v for volume 1 and the old method is # of moles = mass/molar...

Homework Statement How many Fe atoms and how many moles of Fe atoms are in 400.0 g of iron? The Attempt at a Solution Ok. i attempted to find the number of moles by using 400/55.8 to get 7.17 but that is wrong?! please tell me ehy this is wrong. i set up a proportion like this...

10 moles of an ideal gas has a gauge pressure of 2 atm what is new T?? no clue [b]1. Homework Statement [/b 10 moles of an ideal gas has a gauge pressure of 2 atm and a temperature of 200 K. If the volume of the gas is doubled and the pressure dropped to 1 atm., what is the new temperature...

Just a quick question, when calculating C1V1 = C2V2, do I need to account for Mole Rato? Say that C1 had 1 moles required in reaction as opposed to C2 which required 2 moles, would I just multiply C2 by 1/2?

Homework Statement A mixture is completed from 15.0L of ammonia and 15.0L chlorine measured at the same conditions, these compounds react according to the following equation 2NH3(g) + 3Cl2(g) yields N2(g) + 6HCl(g) When the reaction is completed, what is the volume of each gas? Assume...

Equation: 3H2SO4 + Ca3(PO4)2 + 6H20 -> 3[CaSO4×2H2O] + 2H3PO4 Problem: If 2.5×10^5 kg of H2SO4 react, how many moles of H3PO4 can be made? Equations used: 1) kilograms to grams (multiply kilograms by 10^3) 2) Mass to moles (divide given mass by mass of one mole) 3) Moles of substance A to...

Pressure in cylinder, find moles of air entered. Please help! :) Homework Statement The inside of the cylindrical can shown above has cross-sectional area 0.0044 m2 and length 0.28 m. The can is filled with an ideal gas and covered with a loose cap. The gas is heated to 385 K and some is...

Homework Statement what is the number of moles of o2 gas at a pressure of 760 cm of hg in a container of volume 24.63 l at 27 degree c? i read its answer... now i want to ask is this question theoratical or can be calculated ?

Hi there, this is a not a homework question but rather question about the theory behind this problem. Say if someone asks you to calculate the number of moles in 20 ml of a 1M NaOH solution, I would usually say it is going to be 20 mmol as you do 20 ml/1000 ml/L x 1M = 0.02 moles = 20 mmol...

Hi I'm stuck on a homework question on moles. I know the mole formula, but the question doesn't state any needed numbers. Question: Calculate the number of moles of calcium carbonate and hydrochloric acid at the start of the reaction. the reactions is CaCO3+2HCL---CaCl2+CO2+H2O How...

Homework Statement A gas cylinder contains 4.00 x 10^4 cm^3 of hydrogen at a pressure of 2.50 x 10^7 Pa and a temperature of 290 K. The cylinder is to be used to fill balloons. Each balloon, when filled, contains 7.24 x 10^3 cm^3 of hydrogen at a pressure of 1.85 x 10^5 Pa and a temperature...