Chemistry test 2
What is the name for the compound NO2
nitrogen dioxide
What is the formula for sulfurous acid?
H2SO3
What is the name of the covalent compound N2O5?
dinitrogen pentoxide
How many moles of carbon, C, were in the original sample? Express your answer to three significant figures and include the appropriate units
.183 mol
If 5.50 g of the unknown compound contained 0.183 mol of C and 0.367 mol of H, how many moles of oxygen, O, were in the sample?
.183 mol
How many moles of hydrogen, H, were in the original sample? Express your answer to three significant figures and include the appropriate units.
.367 mol
Enter the subscripts for C, H, and O, respectively, separated by commas (e.g., 5,6,7).
1,2,1 CH2O
What is the formula weight of Mg(NO3)2?
148.3 amu
Phosphoric acid reacts with magnesium hydroxide to produce magnesium phosphate and water via the following reaction: ?H3PO4+?Mg(OH)2→?Mg3(PO4)2+?H2O Balance the equation, then enter the coefficients, in order, in the answer box. Enter four integers separated by commas.
2,3,1,6
How many molecules are contained in a 7.75-g sample of dimethylmercury? Express your answer in molecules to three significant figures.
2.02×1022 molecules
The figure (Figure 1) shows the reaction of element A (lavender spheres) with element B (tan spheres). Write the balanced chemical equation for this reaction in terms of A and B.
2A+3B2→2AB3
Calculate the formula weight of ethanol, C2H5OH
46.1 amu
The molecular formula mass of this compound is 150 amu . What are the subscripts in the actual molecular formula? Enter the subscripts for C, H, and O, respectively, separated by commas (e.g., 5,6,7).
5,10,5
What is the mass percentage of each element in the compound Al2O3
52.9% and 47.1% find mollar mass. and divide
How many moles of each element are in this sample? Enter the number of moles of carbon followed by the number of moles of hydrogen, separated by a comma.
6.7,20
You carefully weigh out 17.00 g of CaCO3 powder and add it to 68.85 g of HCl solution. You notice bubbles as a reaction takes place. You then weigh the resulting solution and find that it has a mass of 78.88 g . The relevant equation is CaCO3(s)+2HCl(aq)→H2O(l)+CO2(g)+CaCl2(aq) Assuming no other reactions take place, what mass of CO2 was produced in this reaction?
6.97 g
A hydrocarbon is a compound that contains mostly carbon and hydrogen. Calculate the percent composition (by mass) of the following hydrocarbon: C 5 H 12 . Enter the percentages of carbon and hydrogen numerically to four significant figures, separated by commas.
83.2%, 16.8% mass percent=mass of element / mass of compound×100%
A certain ionic compound is made entirely of aluminum and oxygen.
Al2O3
Determine the molecular formula for the unknown if the molecular mass is 60.0 amu and the empirical formula is CH2O.
C2H4O2
What is the empirical formula of a substance that contains 0.183 mol of carbon, 0.367 mol of hydrogen, and 0.183 mol of oxygen?
CH2O
Based on the mole ratio you determined in Part C, what is the empirical formula of this compound? Express your answer as a chemical formula
CH3
What is the formula for the compound methane
CH4
What is the formula for chlorous acid?
HClO2
Which of these compounds is not a base NaOH CH3NH2 Zn(OH)2 HF
HF
Give the empirical formula of dimethylmercury
HgC2H6
What is the name of the acid whose formula is HI?
Hydroiodic acid
What is the formula for the compound nitrogen monoxide?
NO
What is the empirical formula for the compound P4O6?
P2O3
What is the formula for the compound tetraphosphorus decoxide
P4O10
chemical formula for quartz
SiO2
What is the name of the covalent compound CCl4
carbon tetra chloride
What is the name of the acid whose formula is H2CO3?
carbonic acid
A certain metal hydroxide, M(OH)2, contains 32.8% oxygen by mass. What is the identity of the metal M? Enter the full name of the element.
copper Mass of oxygen32.8g moles of oxygen 2.05(/16) moles of hydrogen2.05(= in formula) mass of hydrogen 2.05g (*1) Mass of metal 65.15g (by difference from 100) moles of metal 1.03(O /2) so we have 1.03 moles of metal in 65.15 g mass of 1 mole = 63.56 g copper !!
B2H6
diboron hexahydride
How many grams of each element are in this sample? Enter the number of grams of carbon followed by the number of grams of hydrogen, separated by a comma (e.g., 30.0,70.0).
mass of C, mass of H = 80.0,20.0 g
How much does one sucrose molecule weigh in grams? Express your answer with the appropriate units.
mass of one molecule of sucrose = 5.68×10−22 g *342 g/mol, divided by avogadros number
What is the percentage of mercury (by mass) in the sample? Express your answer as a percent to four significant figures.
mass percent of Hg = 86.96 %
How many oxygen atoms are in 2.80 g of quartz?
number of O atoms = 5.62×1022 *find molar mass, divide 2.80 by molar mass. use avogadros number to get rid of moles. and multiply by 2
Sr(OH)2
strontium hydroxide
