Calculating moles when given amount of atoms
A (N2H5)2 C3H4O4 has 1.084 x 10^24 carbon atoms. ? moles of hydrogen atoms are there in this sample
The atomic weight of hydrogen is 1.00794
There are 10 hydrogen in the given sample which is = 10.0794 atomic weight within the sample.
How do I use the amount of carbon atoms to determine how many moles of hydrogen atoms are in the sample?
https://brainmass.com/chemistry/composition-stoichiometry/calculating-moles-when-given-amount-of-atoms-60379
Solution Preview
This stuff with number of atoms/moles etc. becomes sort of circular, it causes many students confusion. One day it will just become second nature to you if you keep working on problems.
For this question, make sure you keep the stoichiometry in mind: there are more than 10 H atoms in this molecule if I have it correct - there are ...
Solution Summary
This solution involves finding moles of atoms.
Atom of Tin and Sn Molecules
An atom of tin (Sn) has a diameter of about 2.8 x 10 -8 cm.
a. What is the radius of a tin atom. ?
_________________Angstroms (A) and ________________m
b. how many Sn atoms would have to be placed side by side to span a distance of 6.0 um?
_________________________number os Sn atoms
c. if the atom is assumed to be a sphere, what is the volume in m 3 of a single Sn atom?
_______________________m3
2. fill in the gap in the following table, assuming each column represents a neutral atom.
Symbol / 121Sb / / / / /
Protons / 45 / / / 94 /
Neutrons/ / 58 / 50 / / /
Electrons/ / / 38 / 52 / /
Mass no./ / / / 127 / 239
3. the element lead (Pb) consists of four naturally occurring isotopes with atomic masses 230.97302 , 205.97444, 206.97587, and 207.97663 amu. The relative abundances of these four isotopes are 1.4, 24. , 22.1 and 52.4% respectively. From these data calculate the atomic weight of lead.
____________________AW Pb
4. using the periodic table, predict the charges of the common ions in the following elements.
Element / Charge
a. Sr
b. Sc
c. P
d. I
e. Se
5. predict the chemical formula of the compounds formed by the following pairs of ions.
Compound / Formula
a. Cu+ and S2-
b. Fe3+ and O2-
c. Hg2+ and CO32-
d. Ca2+ and AsO43-
e. NH4 and CO32-
6. name the following inonic compounds
Compound / Name
a. Li2O
b. NaCIO
c. Sr(CN)2
d. Cr(OH)3
e. Fe2(CO3)3
f. Co(NO3)2
g. (NH4)2 SO3
h. NaH2PO4
i. KMnO4
j. Ag2Cr2O7
7. give the formula for each of the following ionic compounds
Ionic compound Formula
a. sodium phosphate
b. cobalt(II) nitrate
c. barium bromate
d. copper(II) perchlorate
e. magnesium hydrogen carbonate
f. chromium (III) acetate
g. potassium dichromate
8. Galluim (Ga) consists of two naturally occurring isotopes with masses of 68.926 and 70. 925 amu.
a. how many protons and neutrons are in the nucleus of each isotopes? Writh the complete atomic symbol for each, showing the atomic number and mass number.
____Symbol/_______________
____/ /_______________
_____/ /_______________
b. the average atomic mass of Ga is 69.72 amu. Calculate the abundance of each isotope.
9. iodic acid has the molecular formula HIO3. write the formulas for the following.
a. the iodate anion
b. periodate anino
c. hypoiodite aninon
d. hypoiodous acid
e. periodic acid
10. Elements in the same group of the periodic table often form oxyaninos with the same general formula. The anions are also named in a similar fashion. Based on these observations suggest a chemical formula or name as appropriate for each of the following ions.
a. BrO-4
b. Seo3 2-
c. Arsenate ion
d. Hydrogen tellurate ion
11. balance the following equations
a. Li(s) + N2(g) ----Li3N(s)
b. La2O3(s) + H2O(l) -- La(OH)3(aq)
c. NH4NO3(s) ---- N2(g) + O2(g) + H2O(g)
12. write a balanced chemical equation for the reaction that occurs when
a. aluminum metal undergoes a combination reaction with O2(g)
b.copper(II) hydroxide decomposes into copper(II) oxide and when water heated
c. heptane C7H16(l) burns in air
d. the gasoline additive MTBE (methyl tert-butyl ether) C5H12O(l) burns in air
13. calculate the percentage by mass of the indicated element in the following compounds.
a. carbon in acetylene C2H2 a gas used in welding
b. hydrogen in ascorbic acid, HC6H7O6 also known as vitamin C
c. Hydrogen in ammonium sulfate, (NH4)2SO4 a substance used as a nitrogen fertilizer
d. platinum in PtCl2(NH3)2 a chemotherapy agent called cisplatin
e. oxygen in the female sex hormone estradiol C18 H24 O2
f. carbon in capsaicin, C18 H27 NO3 the compound that gives the hot taste to chili peppers
14. what is the mass in grams of a mole of 12C?
a._________________________g
b. how many carbon atoms are present in a mole of 12C?
15. Epsom salts, a strong laxative used in veterinary medicine, is a hydrate, which means that a certain number of water molecules are included in the solid structure. The formula for Epsom salts can be written as MgSO4 *xH2O, where x indicates the number of moles of H2O per mole of MgSO4. when 5.061 of this hydrate is heated to 250*C, all the water of hydration is lost leaving 2.472 g of MgSO4. what is the value of x?
Solution
16. Iron ore sample contains Fe2O3 together with other substances. Reactions of the ore with CO produces iron metal.
Fe2O3(s) + CO(g) --- CO2(g)
a. Balance this equation
b. calculate the number of grams of CO that can react with 0.150 kg of Fe2O3
__________g CO
c. calculate the number of grams fo Fe and the number of grams of CO2 formed when 0.150 kg of Fe2O3 reacts.
d. show the your calculations in parts b and c are consistent with the law of conservation of mass
17. calculate the following quantites
a. mass in grams of 1.906 x 10-2 mol Bal2
________________________g
number of moles of NH4CI in 48.3g of this substance
________________________________moles
number of molecules in 0.05752 mol HCHO2
______________________molecules
d. number of O atoms in 4.88 x 10 -3 mol AI(NO)3
____________________________atoms
18. determine the empirical formula of each of the following compounds if a sample contains
Contents / empirical formula
a. 0.104 mol K, 0.052 mol C
0.156 mol O
b. 5.28 g Sn and 3.37g F
c. 87.5% N and 12.5% H by mass
19. aluminum hydroxide reacts with sulfuric acid as follows
2 AI(OH)3(s) + 3 H2SO4(aq) ----- Ai2(SO4)3(aq + 6 H2O(I)
a. which reagent is the limiting reactant when 0.500 mol AI(OH)3 and 0.500 mol H2SO4 are allowed to react
b. how many moles of AI2(SO4)3 can form under these conditions?
c. How may moles of the excess reactant remain after the completion of the reaction?
a._______________________limiting reagent
b. _____________________________mols AI2(SO4)3
C.______________________________________________excess reagent (mols)
20. solutions fo sulfuric acid and lead (II) acetate react to form solid lead (II) sulfate and a solution fo acetic acid. If 7.50 g of sulfuric acid and 7.50 g of lead (II) acetate are mixed, calculate the number of grams of sulfuric acid, lead (II) acetate, lead(II) sulfate, and acetic acid present in the mixture after the reaction is complete
___________________________g H2SO4
_____________________________g lead(II) acetate
_____________________________g lead(II) sulfate
____________________________g acetic acid
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