COMPILED QUESTIONS Flashcards
The discovery of neutron by bombarding beryllium atom with alpha particle accompanies the formation of ___ atom
12C
Why do alkali metals tend to be more reactive than alkaline earth metals
Alkali metals have lower ionization energies
Energy change when widely separated gaseous ions come together to form crystalline substance
Lattice Energy
What is the maximum number of electrons for the quantum number, n=2, ml=0
4
What is the frequency (s-1) pf electromagnetic radiation that has a wavelength of 0.53m?
5.7X10^8
The presence of a common ion will result in ___ of the solubility product constant
no change
An element X is found to combine with oxygen to form a compound with molecular formula X4O6. If 8.40 grams of the element X combine with 6.50 grams of oxygen, the atomic weight of the element is
31 g/mol
Which of the following devices converts radioactive emissions to light for detection
scintillation counter
Starting with 1 g of Sr-90, 0.953 grams remains after 2 years. Calculate the initial activity of Sr-90 in Ci?
140
Among the following reactions the that is not most likely to happen is
A.) 2Al(s) + 3H2O(l) — Al2O3(s) + 3H2
A c-14 Assay of a human bone found by an archaeologist revealed that C-14 Activity was one-tenth that the C-14 activity of living matter. What is the age of the bone? half life of c-14 is 5730 years.
19,000 years
Type of covalent bond where one atom furnishes both electrons in a bond
coordinate covalent
Which of the following is most likely to be a reversible reaction?
B.) KNO3 + NaCl — KCL + NaNO2
Magnesium mixture is added to an acidic solution of an unknown substance and therefore forms a white crystalline precipitate. The unknown substance most likely contained__-_
PO4-3
The half life for the process 234U-206 Pb is 4.5x109 years. A mineral sample containes 50,0 mg of 234U and 14 mg of 206 Pb. what is the age of the mineral?
1.8 x109 years old
Which of the following statements is not correct regarding preparations of standard NaOH solutions?
d.) If NaOH solutions is used in titration reactions in the basic range, small amount carbonate contamination causes no significant error
if 10 grams sample of powdered cleanser was dissolved in water to make 500 ml solution. About 20 ml aliquot was titrated with 0.0234 M HCl to the methyl red endpoint. Assuming the sample contains Na2B4o7 (201.22), calculate the wt% Na2B4O7 in the sample.
b. 6.18%
Which of the following analysis usually involved back titration?
kjeldahl analysis using boric acid to collect ammonia
How many milliliters of 0.250 M H2SO4 must be added to 75 mL of 0.300 N HCl in order that the resulting solution will be 0.400 N as an acid?
75 ml
What is the endpoint reaction for the titration using Mohr method?
C.) 2g + CrO4 —- Ag2CrO4
For the analysis of Ca2+ via replacement titration involving EDTA, Which of the following statements if False?
all of these statements is true
Treatment of hydroxylamine (H2NOH) with an excess Fe (II) results in the formation of N20 and an equivalent amount of Fe(II): 2H2NOH +4FE3+ —- N2O(G) + 4Fe2+ +4H + H2O. Calculate the molar concentration of an H2NOH solution if the Fe(II) produced by treatment of a 50 ml aliquot required 19.83 ml of 0.0325 M K2Cr2O7
d.) 0.03867 M
A 0.1401 g sample of a purified carbonate was dissolved in a 50 ml of 0.1140 M HCl and boiled to eliminate CO2. Back titration of the excess HCl required 24.21 mL of 0.09802 M NaOH. Identify the carbonate
MgCO3
The mercury in a 0.8142-g sample was precipitated with an excess of paraperiodic acid, HsIO: 5Hg2+ + 2HsIO6-Hgs(106)2+10H The precipitate was filtered, washed free of precipitating agent, dried and weighed, and 0.4114 g was recovered. Calculate the percentage of HgCl, in the sample.
d.) 41.45%
A 3650-mg sample containing bromate and bromide was dissolved in sufficient water to give 250.0 mL. After acidification, silver nitrate was added to a 25.00 mL aliquot where the resulting precipitate was filtered, washed and then redissolved in an ammoniacal solution of potassium tetracyanonickelate(II) according to the reaction:
Ni(CN)-2 + 2 AgBr(s) 2 Ag(CN)2-1 + Ni-2 + 2 Br-1
The liberated nickel ion required 26.73 mL of 0.02089 M EDTA. The bromate ion in a 10.00 ml. aliquot was reduced to bromide with As prior to the addition of silver nitrate. The same procedure was followed and the released nickel ion was titrated with 21.94 mL of the EDTA solution. Calculate the percentage of impurity in the sample. Br (79.904)
C.) 41.17 (not sure)
