A balloon filled with He(g) contains the same number of atoms as a similar balloon filled with Ne(g). Both balloons are at the same temperature and pressure as the air around them. Which one of the following statements is correct? Both balloons have the same volume. Both balloons have the same mass of gas. Both balloons will fall to the ground if released. Both balloons have the same density of gas. Helium balloon will float in air if released, but the neon Neon balloon will fall to the ground.

You have two distinct gaseous compounds made from element X and element Y. The mass percents are as follows: Compound I: 30.43% X, 69.57% Y Compound II: 63.64% X, 36.36% Y In their natural standard states, element X and element Y exist as gases. (Monatomic? Diatomic? Triatomic? That is for you to determine.) When you react gas X with gas Y to make the products, you get the following data (all at the same pressure and temperature): 1. volume gas X + 2 volumes gas Y2 volumes compound I 2. volumes gas X + 1 volume gas Y2 volumes compound II Assume the simplest possible formulas for reactants and products in the chemical equations above. Then, determine the relative atomic masses of element X and element Y.

Estimating the radius of a lead atom. (a) You are given a cube of lead that is 1.000 cm on each side. The density of lead is 11.35 g/ cm3. How many atoms of lead are in the sample? (b) Atoms are spherical; therefore, the lead atoms in this sample cannot fill all the available space As an approximation, assume that 60% of the space of the cube is filled with spherical lead atoms. Calculate the volume of one lead atom from this information. From the calculated volume (V) and the formula (4/3) 3 for the volume of a sphere, estimate the radius (r) of a lead atom.

62 Ammonium dinitramide (ADN), NH4N(NO2)2, was considered as a possible replacement for aluminium chloride as the oxidizer in the solid fuel booster rockets used to launch the space shuttle. When detonated by a spark, AND rapidly decomposes to produce a gaseous mixture of N2,O2, and H2O. (This is not a combustion reaction. The ADN is the only reactant.) The reaction releases a lot of heat, so the gases are initially formed at high temperature and pressure. The thrust of the rocket results mainly from the expansion of this gas mixture. Suppose a 2.3-kg sample of ADN is denoted and decomposes completely to give N2,O2, and H2O. If the resulting gas mixture expands until it reaches a temperature of 100°C and a pressure of 1.00 atm, what volume will it occupy? Is your answer consistent with the proposed use of ADN as a rocket fuel?