Skip to main content
Ch.18 - Chemistry of the Environment
Chapter 18, Problem 47

Magnesium ions are removed in water treatment by the addition of slaked lime, Ca(OH)2. Write a balanced chemical equation to describe what occurs in this process

Verified Solution

Video duration:
1m
This video solution was recommended by our tutors as helpful for the problem above.
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Chemical Reactions

A chemical reaction involves the transformation of reactants into products through the breaking and forming of chemical bonds. In the context of water treatment, understanding how magnesium ions interact with slaked lime is essential to write a balanced equation that accurately represents the process.
Recommended video:
Guided course
03:37
Chemical Properties

Balancing Chemical Equations

Balancing a chemical equation ensures that the number of atoms for each element is the same on both sides of the equation, adhering to the law of conservation of mass. This process involves adjusting coefficients to reflect the correct stoichiometry of the reactants and products involved in the reaction.
Recommended video:
Guided course
01:32
Balancing Chemical Equations

Slaked Lime in Water Treatment

Slaked lime, or calcium hydroxide (Ca(OH)2), is commonly used in water treatment to precipitate hardness-causing ions, such as magnesium (Mg²⁺). When added to water, it reacts with magnesium ions to form insoluble magnesium hydroxide, which can then be removed from the water, thus softening it.
Recommended video:
Guided course
01:23
Reaction with Water
Related Practice
Textbook Question

The enthalpy of fusion of water is 6.01 kJ/mol. Sunlight striking Earth's surface supplies 168 W per square meter (1 W = 1 watt = 1 J/s). (b) The specific heat capacity of ice is 2.032 J/g°C. If the initial temperature of a 1.00 square emter patch of ice is -5.0°C, what is its final temperature after being in sunlight for 12 h, assuming no phase changes and assuming that sunlight penetration uniformly to a depth of 1.00 cm?

3702
views
Textbook Question

The Ogallala aquifer described in the Closer Look box in Section 18.3, provides 82% of the drinking water for the people who live in the region, although more than 75% of the water that is pumped from it is for irrigation. Irrigation withdrawals are approximately 18 billion gallons per day. (a) Assuming that 2% of the rainfall that falls on an area of 600,000 km2 recharges the aquifer, what average annual rainfall would be required to replace the water removed for irrigation?

400
views
Textbook Question

The organic anion

is found in most detergents. Assume that the anion under-goes aerobic decomposition in the following manner: C18H29SO3- + 51 O2 → 36 CO2(aq) + 28 H2O (l) + 2 H+(aq) + 2 SO42-(aq) What is the total mass of O2 required to biodegrade 10.0 g of this substance?

421
views
Textbook Question

In the lime soda process once used in large scale munici-pal water softening, calcium hydroxide prepared from lime and sodium carbonate are added to precipitate Ca2+ as CaCO3(s) and Mg2+ as Mg(OH)2(s): Ca2+(aq) + CO32-(aq) → CaCO3(s) Mg2+(aq) + 2 OH-(aq) → MgOH2(aq) How many moles of Ca(OH)2 and Na2CO3 should be added to soften (remove the Ca2+ and Mg2+) 1200 L of water in which [Ca2+] = 5.0x10-4 M and [Mg2+] = 7.0x10-4 M?

852
views
Textbook Question

(b) Draw the Lewis structures of two example THMs.

739
views
Textbook Question

A reaction for converting ketones to lactones, called the Baeyer–Villiger reaction,

is used in the manufacture of plastics and pharmaceu- ticals. 3-Chloroperbenzoic acid is shock-sensitive, how- ever, and prone to explode. Also, 3-chlorobenzoic acid is a waste product. An alternative process being developed uses hydrogen peroxide and a catalyst consisting of tin deposited within a solid support. The catalyst is readily recovered from the reaction mixture. (a) What would you expect to be the other product of oxidation of the ketone to lactone by hydrogen peroxide?

727
views