What do stanzas $1-3$ reveal about the character of the man who "knew his native land through iron gates" and kept a pair of Dobermans-large dogs that are often used as guard dogs?

The equilibrium constant $K_{\mathrm{a}}$ for the reaction

$$\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}^{3+}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{5}(\mathrm{OH})^{2+}(a q)+\mathrm{H}_{3} \mathrm{O}^{+}(a q)$$

is $6.0 \times 10^{-3}.$ Will a 1.0-M solution of iron(II) nitrate have a higher or lower pH than a 1.0-M solution of iron(III) nitrate? Explain.

Calculate the mass in grams of each the following.

$$\\$$

(a)

$$2.5\;\text{mol of aluminum},$$

(b)

$$1.25\times10^{-3}\;\text{mol of iron},$$

(c)

$$0.015\;\text{mol of calcium},$$

(d)

$$653\;\text{mol of neon}$$

It is desired to deliver 60 m³/h of water at 20°C through a horizontal asphalted cast iron pipe. Estimate the pipe diameter that will cause the pressure drop to be exactly 40 kPa per 100m of pipe length.

The photograph below (a) shows what occurs when a solution of iron (III) nitrate is treated with a few drops of aqueous potassium thiocyanate. The nearly colorless iron(III) ion is converted to a red $\left[\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_5 \mathrm{SCN}\right]^{2+}$ ion. (This is a classic test for the presence of iron(III) ions in solution.)

$$\begin{align*} \begin{aligned} &{\left[\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{3+}(\mathrm{aq})+\mathrm{SCN}^{-}(\mathrm{aq}) \rightleftarrows} \\ &{\left[\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_5 \mathrm{SCN}\right]^{2+}(\mathrm{aq})+\mathrm{H}_2 \mathrm{O}(\ell)} \\ & \end{aligned} \end{align*}$$

Adding KSCN

Iron ore is converted to iron metal in a reaction with carbon.

$$2 \mathrm{Fe}_2 \mathrm{O}_3(\mathrm{~s})+3 \mathrm{C}(\mathrm{s}) \rightarrow 4 \mathrm{Fe}(\mathrm{s})+3 \mathrm{CO}_2(\mathrm{~g})$$

If $6.2 \mathrm{~mol} \mathrm{of} \mathrm{Fe}_2 \mathrm{O}_{\mathrm{g}}(\mathrm{s})$ is used, what amount of $\mathrm{C}(\mathrm{s})$ is needed, and what amounts of $\mathrm{Fe}$ and $\mathrm{CO}_2$ are produced?

Iron metal has a density of $7.86 \mathrm{~g} / \mathrm{cm}^3$ and a molar mass of $55.85 \mathrm{~g}$. Use this information together with the data in Previous question to calculate a value for Avogadro's number.

Iron metal has a density of $7.86 \mathrm{~g} / \mathrm{cm}^3$ and a molar mass of $55.85 \mathrm{~g}$. Use this information together with the data in Problem $10.125$ to calculate a value for Avogadro's number.

Use the table above to determine the identity of a substance with a mass of 108 g and a volume of 40 cm$^3$.

Explain why $\mathrm{FeCl}_2$ is named iron(II) chloride, using a Roman numeral, and $\mathrm{BaCl}_2$ is named barium chloride, using no Roman numeral. Why do neither use prefixes?

Suppose your friend is $510$ m away along a long iron railing while you have your ear to that railing. She taps the railing with a stone. How long will the sound take to reach your ear?

A 5-metre iron bar is to be produced. The bar may not deviate by more than 1mmfrom its stated length. Write a specification for the bar’s length x in metres:

(a) by using a double inequality;

(b) with the aid of an absolute-value sign.

The equilibrium constant $K _ { \mathrm { a } }$ for the reaction $\mathrm { Fe } \left( \mathrm { H } _ { 2 } \mathrm { O } \right) _ { 6 } ^ { 3 + } ( a q ) + \mathrm { H } _ { 2 } \mathrm { O } ( l ) \rightleftharpoons \mathrm { Fe } \left( \mathrm { H } _ { 2 } \mathrm { O } \right) _ { 5 } ( \mathrm { OH } ) ^ { 2 + } ( a q ) + \mathrm { H } _ { 3 } \mathrm { O } ^ { + } ( a q )$ is $6.0 \times 10 ^ { - 3 }.$ Will a 1.0 M solution of iron(II) nitrate have a higher or lower pH than a 1.0 M solution of iron(III) nitrate? Explain.

A current of $1.5 \mathrm{~A}$ flows through the windings of a large, thin toroid with $200$ turns per meter. If the toroid is filled with iron for which $\chi=3.0 \times 10^3$, what is the magnetic field within it?