Concept explainers
The force of attraction due to gravity follows an equation similar to Coulomb’s law:
Where
(a) Calculate the force of gravitational attraction between Earth and the Sun if the mass of Earth equals
(b) Assuming that the Sun and Earth would have the same magnitude but opposite charges, what charge is necessary to provide a coulombic force that equals the gravitational force between the Sun and Earth? How many moles of electrons is that? To put your answer in perspective, consider that if earth were composed of pure iron, it would contain about
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Physical Chemistry
- Helium is the lightest noble gas and the second most abundant element (after hydrogen) in the universe. (a) The radius of a helium atom is 3.1x10-11 m; the radius of its nucleus is 2.5x10-15 m. What fraction of the spherical atomic volume is occupied by the nucleus (V of a sphere 5 4/ 3πr3)? (b) The mass of a helium-4 atom is 6.64648x10-24 g, and each of its two electrons has a mass of 9.10939x10-28 g. What fraction of this atom’s mass is contributed by its nucleus?arrow_forward2. THE FORCE BETWEEN TWO CHARGES IS 1000 N. ONE HAS A CHARGE OF 2X 10-5 C, AND THE OTHER HAS A CHARGE OF 5 X 10 C. WHAT IS THE DISTANCE BETWEEN THEM?arrow_forwardChoose one group of representative elements (main group elements) and discuss its chemistry by specifying (i) one of its properties, (ii) citing one important reaction that one member of the group undergoes (write the chemical equation), and (iii) mentioning one of the applications/uses of the members of the group. Your answers to i-iii must consist of no more than 20 words each.arrow_forward
- (d) the ion with 74 electrons, 116 neutrons, and a +3 chargearrow_forwardHand written solutions are strictly prohibited.arrow_forward2. A charged particle is caused to move between two electrically charged plates, as shown here. +) (a) Why does the path of the charged particle bend? (b) What is the sign of the electrical charge on the particle? (c) As the charge on the plates is increased, would you expect the bend- ing to increase, decrease, or stay the same? (d) As the mass of the particle is increased while the speed of the particles remains the same, would you expect the bending to increase, decrease, or stay the same?arrow_forward
- A mass spectrometer is being used to separate common oxygen-16 from the much rarer oxygen-18, taken from a sample of old glacial ice. (The relative abundance of these oxygen isotopes is related to climatic temperature at the time the ice was deposited.) The ratio of the masses of these two ions is 16 to 18, the mass of oxygen-16 is 2.66 ✕ 10−26 kg, and they are singly charged and travel at 7.40 ✕ 106 m/s in a 1.40 T magnetic field. What is the separation (in m) between their paths when they hit a target after traversing a semicircle?arrow_forwardSome salts have water of hydration and are called hydrated salts. A 3.216 g sample of a hydrated salt of Na,B,O, · XH20 is heated to drive off the water of hydration. The resulting anhydrous salt, which has a mass of 2.222 g, contains 0.5077 g of sodium, 0.4775 g of boron, and some oxygen. What are the values of x, y, z and X in the above salt? Write the numerical values for x, y and z next to the symbol of the element, and X, before H20. Na H2O Barrow_forwardv. Answer true or false. (a) Mendeleev discovered that, when elements are arranged in order of increasing atomic weight, certain sets of properties recur periodically. (b) Main-group elements are those in the columns 3A to 8A of the Periodic Table. (e) Nonmetals are found at the top of the Periodic Table, metalloids in the middle, and metals at the bottom. (d) Among the 116 known elements, there are approximately equal numbers of metals and nonmetals. (e) A horizontal row in the Periodic Table is called a group. () The Group 1A elements are called the "alkali metals." (g) The alkali metals react with water to give hydrogen gas and a metal hydroxide, MOH, where “M" is the metal. (h) The halogens are Group 7A elements. (1) The boiling points of noble gases (Group 8A elements) increase in going from top to bottom of the column.arrow_forward
- A new compound has the empirical formula GaCl2. Thissurprises some chemists who, based on the position of gallium in the periodic table, expect a chloride of gallium to have the formula GaCl3 or possibly GaCl. They suggest that the “GaCl2” is really Ga[GaCl4], in which the bracketed group behaves as a unit with a -1 charge. Suggest experiments to test this hypothesisarrow_forwardChromium reacts with oxygen to form three different compounds, X, Y and Z. It was found that, for every gram of chromium in Compounds X, Y and Z, there were 0.308 g, 0.462 g and 0.924 g of oxygen, respectively. (a) Show that the above data illustrate Dalton’s Law of Multiple Proportions.(b) Using these data, derive simple formula of compounds X, Y and Z.arrow_forwardLook up the following information for the element iridium: (i) number of protons, neutrons, and electrons; (ii) atomic number and average atomic mass; (iii) the charge of the anion(s) or cation(s) that it commonly forms; (iv) the mass of its two most common isotopes and the number of protons and neutrons in each one. Also, comment briefly on the presence of this element in meteorite craters and the significance of this observation.arrow_forward
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