Mastering Chem Unit 2A Chpt.1

Determine the number of significant figures in the measurement 0.0030 s? Express your answer numerically as an integer.

2

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 The hydroxide formula is Cu(OH)2

Part D When heated, solid copper(II) carbonate decomposes to solid copper(II) oxide and carbon dioxide gas. Give the balanced chemical equation (including phases) that describes this reaction. Indicate the phases using abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively.

CuCO3(s)→CuO(s)+CO2(g)

Part A What are the subscripts in the empirical formula of this compound? Enter the subscripts for C, H, and O, respectively, separated by commas (e.g., 5,6,7).

1, 2, 1 The empirical formula of this compound is CH2O

Compute 1240.64/12.5. Round the answer appropriately. Express your answer numerically using the proper number of significant figures.

1240.64/12.5= 99.3

Part A How many shifts must you work if you wish to wash 10 loads of laundry? Express your answer numerically as an integer

2 shifts

Part B 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.

2,3,1,6 Notice that the equation shows a total of 12 hydrogen atoms, 2 phosphorus atoms, 3 magnesium atoms, and 14 oxygen atoms on each side

Part B Solid lithium metal and diatomic fluorine gas react spontaneously to form a solid product. Give the balanced chemical equation (including phases) that describes this reaction. Indicate the phases using abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively. Express your answer as a chemical equation

2Li(s)+F2(g)→2LiF(s)

Compute 3.5×4.48697. Round the answer appropriately. Express your answer numerically using the proper number of significant figures.

3.5×4.48697= 16

Compute 4.659×10^4−2.14×10^4. Round the answer appropriately. Express your answer as an integer using the proper number of significant figures (e.g. 12300)

4.659×10^4−2.14×10^4= 25200

Round the value 44.981g to three significant figures. Express your answer numerically using three significant figures.

45.0g The number 44.981 is closer to 45.0 than it is to 44.9

Part B The molecular formula mass of this compound is 240 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).

8, 16, 8

Part D 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

Part A Classify each of the following reactions: a.) C3H8(g)+5O2(g)→3CO2(g)+4H2O(g) b.) MgCO3(s)→MgO(s)+CO2(g) c.) H2(g)+I2(g)→2HI(g) d.) CaO(s)+H2O(l)→Ca(OH)2(aq) e.) 2Cu(NO3)2(s)→2CuO(s)+4NO2(g)+O2(g)

Decomposition - b,e Combination - c,d Combustion - a

Part A What is the empirical formula for the compound P4O6? Express your answer as a chemical formula

P2O3

A hydrocarbon is a compound that contains mostly carbon and hydrogen. Calculate the percent composition (by mass) of the following hydrocarbon: C4H10. Enter the percentages of carbon and hydrogen numerically to four significant figures, separated by commas

carbon, hydrogen =82.66, 17.34%

Part B Calculate the mass of 1.00×10^24(a septillion) molecules of water. Express the answer numerically in grams

29.9 g This value is close to the mass of a fluid ounce of water (29.6 mL). Now you know that one fluid ounce of water contains approximately 1024 (a trillion) molecules

Part A 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. Express your answer as a chemical equation.

2A+3B2→2AB3

Part C You carefully weigh out 15.00 g of CaCO3 powder and add it to 60.75 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 69.60 g. The relevant equation is CaCO3(s)+2HCl(aq)→H2O(l)+CO2(g)+CaCl2(aq) Assuming no other reactions take place, what mass of CO2CO2 was produced in this reaction? Express your answer to three significant figures and include the appropriate units

6.15 g

Compute 9.3456+2140.56. Round the answer appropriately. Express your answer numerically using the proper number of significant figures.

9.3456+2140.56= 2149.91

Part B 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

Part C The fuel used in many disposable lighters is liquid butane, C4H10. How many carbon atoms are in 3.00 g of butane? Express your answer numerically in atoms

1.24×10^23 carbon atoms

Part A A flask contains 0.260 mol of liquid bromine, Br2. Determine the number of bromine molecules present in the flask. Express your answer numerically in molecules.

1.57×10^23 molecules

Part B How many loads of laundry can you wash if you work 3 shifts? Express your answer numerically as an integer.

15 loads

Determine the number of significant figures in the measurement 6.07 mm? Express your answer numerically as an integer.

3

Part C How many loads of laundry will each shift pay for if the cost per load rises to 16 quarters? Express your answer numerically as an integer

3 loads

Now that we have put coefficients of 3 in front of CaSO4 and CaCl2, what coefficient should go in front of AlCl3 to balance both the Cl atoms and the Al atoms? 3CaSO4+?AlCl3→3CaCl2+Al2(SO4)3 Express your answer numerically as an integer

?=2

Notice that "SO4" appears in two different places in this chemical equation. SO42− is a polyatomic ion called "sulfate." What number should be placed in front of CaSO4 to give the same total number of sulfate ions on each side of the equation? ?CaSO4+AlCl3→CaCl2+Al2(SO4)3 Express your answer numerically as an integer.

?=3

Now that we have put a coefficient of 3 in front of CaSO4, what coefficient should go in front of CaCl2 to balance calcium (Ca)? 3CaSO4+AlCl3→?CaCl2+Al2(SO4)3 Express your answer numerically as an integer

?=3

Part C Give the balanced chemical equation (including phases) that describes the combustion of butene, C4H8(g). Indicate the phases using abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively. Express your answer as a chemical equation

C4H8(g)+6O2(g)→4H2O(g)+4CO2(g)

Part C 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.

moles of C, moles of H = 6.66, 19.8 mol