What is the sum of the masses of 1 Fe atom + 2 Cl atoms? Enter your answer rounded to four sig figs, without units.

Chalky, white crystals in mineral collections are often labeled borax, which has the molecular formula Na2B4O7 10H2O, when actually they are partially dehydrated samples with the molecular formula Na2B4O7 5H2O, which is more stable under the storage conditions. Real crystals of borax are colorless and transparent. (a) Calculate the percent mass that the mineral has lost when it partially dehydrates. (b) Is the percent boron by mass the same in both compounds?

Is there a difference between a homogeneous mixture of hydrogen and oxygen in a 2:1 mole ratio and a sample of water vapor? Explain.

Which of the following pairs of compounds have the same empirical formula? a. acetylene, C2H2, and benzene, C6H6 b. ethane, C2H6, and butane, C4H10 c. nitrogen dioxide, NO2, and dinitrogen tetroxide, N2O4 d. diphenyl ether, C12H10O, and phenol, C6H5OH

Two general chemistry students working together in the lab weigh out 0.832 g of CaCl2 2 H2O into a crucible. After heating the sample for a short time and allowing the crucible to cool, the students determine that the sample has a mass of 0.739 g. They then do a quick calculation. On the basis of this calculation, what should they do next? (a) Congratulate themselves on a job well done. (b) Assume the bottle of CaCl2 2 H2O was mislabeled; it actually contained something different. (c) Heat the crucible again, and then reweigh it.

Express the composition of each of the following compounds as the mass percents of its elements. a. formaldehyde, CH2O b. glucose, C6H12O6 c. acetic acid, HC2H3O2

The structure of one of the bases in DNA, adenine, is shown here. Which represents the greater mass: 40.0 g of adenine or 3.0 1023 molecules of the compound?

3.96 Methyl cyanoacrylate is the chemical name for the substance sold as Super Glue, and it has the chemical formula C5H5NO2. Calculate the number of molecules of this substance in a 1.0-ounce tube of Super Glue, assuming that the glue is 80% methyl cyanoacrylate by mass.

Arrange the following substances in order of increasing mass percent of nitrogen. a. NO b. N2O c. NH3 d. SNH

3.55 An average person inhales roughly 2.5 g of O2 in a minute. How many molecules of oxygen are inhaled in (a) 1 minute, (b) 1 hour, (c) 1 day by an average person?