Suggest physical change by which 'iron filings and wood chips' can be separated.

In the production of ammonia, the following processes occur.
(a) Air is liquefied at low temperatures and high pressure.
(b) The temperature of the liquid air is raised gradually until the oxygen boils off. Essentially pure liquid nitrogen remains.
(c) Natural gas is treated with steam to produce carbon dioxide and hydrogen. The proportions of the products vary with the composition of the natural gas
(d) Hydrogen and nitrogen (both gases) are combined at high temperatures and pressures. They react to form ammonia gas. Some unreacted hydrogen and nitrogen remain. (e) The gases are cooled until the ammonia liquefies, and then the gaseous hydrogen and nitrogen are recirculated to react again. For each of (a) to (e), indicate whether a physical or chemical change occurs, and briefly explain your choice. For each italicized word or phrase, state whether it refers to an element, a compound, a mixture, or none of these, and briefly explain your choice.

A lump of pure copper weighs $25.305 \mathrm{~g}$ in air and $22.486 \mathrm{~g}$ when submerged in water $(d=0.9982 \mathrm{~g} / \mathrm{mL})$ at $20.0^{\circ} \mathrm{C}$. Suppose the copper is then rolled into a $248 \mathrm{~cm}^2$ foil of uniform thickness. What will this thickness be, in millimetres?

In the production of ammonia, the following processes occur.
(a) Air is liquefied at low temperatures and high pressure.
(b) The temperature of the liquid air is raised gradually until the oxygen boils off. Essentially pure liquid nitrogen remains.
(c) Natural gas is treated with steam to produce carbon dioxide and hydrogen. The proportions of the products vary with the composition of the natural gas.
(d) Hydrogen and nitrogen (both gases) are combined at high temperatures and pressures. They react to form ammonia gas. Some unreacted hydrogen and nitrogen remain. (e) The gases are cooled until the ammonia liquefies, and then the gaseous hydrogen and nitrogen are recirculated to react again. For each of (a) to (e), indicate whether a physical or chemical change occurs, and briefly explain your choice. For each italicized word or phrase, state whether it refers to an element, a compound, a mixture, or none of these, and briefly explain your choice.

In the production of ammonia, the following processes occur.
(a) Air is liquefied at low temperatures and high pressure.
(b) The temperature of the liquid air is raised gradually until the oxygen boils off. Essentially pure liquid nitrogen remains.
(c) Natural gas is treated with steam to produce carbon dioxide and hydrogen. The proportions of the products vary with the composition of the natural gas.
(d) Hydrogen and nitrogen (both gases) are combined at high temperature and pressures. They react to form ammonia gas. Some unreacted hydrogen and nitrogen remain. (e) The gases are cooled until the ammonia liquefies, and then the gaseous hydrogen and nitrogen are recirculated to react again. For each of (a) to (e), indicate whether a physical or chemical change occurs, and briefly explain your choice. For each italicized word or phrase, state whether it refers to an element, a compound, a mixture, or none of these, and briefly explain your choice.

Indicate whether 'freshly squeezed orange juice' is a substance or a mixture; if it is a mixture, indicate whether it is homogeneous or heterogeneous.

In the production of ammonia, the following processes occur.
(a) Air is liquefied at low temperature and high pressure.
(b) The temperature of the liquid air is raised gradually until the oxygen boils off. Essentially pure liquid nitrogen remains.
(c) Natural gas is treated with steam to produce carbon dioxide and hydrogen. The proportions of the products vary with the composition of the natural gas.
(d) Hydrogen and nitrogen (both gases) are combined at high temperature and pressures. They react to form ammonia gas. Some unreacted hydrogen and nitrogen remain. (e) The gases are cooled until the ammonia liquefies, and then the gaseous hydrogen and nitrogen are recirculated to react again. For each of (a) to (e), indicate whether a physical or chemical change occurs, and briefly explain your choice. For each italicized word or phrase, state whether it refers to an element, a compound, a mixture, or none of these, and briefly explain your choice.

Indicate whether 'distilled water' is a substance or a mixture; if it is a mixture, indicate whether it is homogeneous or heterogeneous.

Indicate whether 'red ink' is a substance or a mixture; if it is a mixture, indicate whether it is homogeneous or heterogeneous.

Without doing detailed calculations, explain which of the following objects contains the greatest mass of the element iron. (a) A $1.00 \mathrm{~kg}$ pile of pure iron filings. (b) A cube of wrought iron, $5.0 \mathrm{~cm}$ on edge. Wrought iron contains $98.5 \%$ iron by mass and has a density of $7.7 \mathrm{~g} / \mathrm{cm}^3$. (c) A square sheet of stainless steel $0.30 \mathrm{~m}$ on edge and $1.0 \mathrm{~mm}$ thick. Stainless steel is an alloy (mixture) containing iron, together with $18 \%$ chromium, $8 \%$ nickel, and $0.18 \%$ carbon by mass. Its density is $7.7 \mathrm{~g} / \mathrm{cm}^3$. (d) $10.0 \mathrm{~L}$ of a solution characterized as follows: $d=1.295 \mathrm{~g} / \mathrm{mL}$. This solution is $70.0 \%$ water and $30.0 \%$ of a compound of iron, by mass. The iron compound consists of $34.4 \%$ iron by mass.

Indicate whether 'a wooden beam' is a substance or a mixture; if it is a mixture, indicate whether it is homogeneous or heterogeneous.

List the following in the order of increasing precision, indicating any quantities about which the precision is uncertain: (a) $1400 \mathrm{~km}$; (b) $1516 \mathrm{~kg} ;$ (c) $0.00304 \mathrm{~g}$; (d) $125.34 \mathrm{~cm}$; (e) $2000 \mathrm{mg}$.

Use fundamental definition and statement from Chapters 1 and 2 to establish the fact that $6.022 \times 10^{23} \mathrm{u}=1.000 \mathrm{~g}$

Use fundamental definition and statements from Chapters 1 and 2 to establish the fact that $6.022 \times 10^{23} \mathrm{u}=1.000 \mathrm{~g}$