Chemical equation questions

To practice entering chemical expression answers

When available, open the Introduction to Mastering assignment and select the the Introduction to Chemical Answers item. This assignment provides practice items for different kinds of questions. You can usually return to this assignment for practice or to refresh your memory about entering answers at any time during the course.

Overview: Answering on a computer or mobile device

Toolbar for these questions on a computer:

Toolbar for these questions on a mobile device

	Enter answers on a computer	Enter answers on a mobile device* (tablet or smartphone)
Toolbar Don't have a toolbar with the answer box? See alternate instructions.	Use the Templates menu for special formats like subscript and reaction arrows. Use the Symbols menu for Greek letters. To undo, redo, and reset the answer box to its original state: Use toolbar buttons. To view or print keyboard shortcuts or this Help topic: Select buttons on the right.	Tap the answer box for the toolbar to appear beneath it. Choose buttons from the Letters, Numeric, Templates, and Symbols menus to compose your answer. To undo, redo, and reset the answer box to its original state: Use toolbar buttons on the right.
Keyboard for letters and numbers	Use your physical keyboard to enter letters, numbers, and other characters. See info below for characters you can or cannot use in your answers.	Choose either the Letters menu or the Numeric menu for alphanumeric characters and some math symbols. To switch between lowercase and uppercase keys: Choose the arrow button from the Letters menu.
Keyboard shortcuts for special formats (like subscript)	It can be faster to use keyboard shortcuts instead of the Templates menu to insert special formats.	For keyboard shortcuts that begin with \ (backslash), choose \ from the Letters menu.
Cursor control in your answer	Use your keyboard arrow keys (, , , ) to move the cursor in your answer. It can be easier to use arrow keys instead of a mouse or other input device to reposition your cursor.	Use your finger or other input device to position the cursor in your answer. For finer cursor control on a phone: Enlarge your view of the answer box before moving the cursor. If cursor control on your phone is challenging: Consider using your computer or a tablet.

* Answering assignment questions in Mobile View requires a student account. When you sign in on a mobile device, you can check whether your browser supports Mastering mobile content.

Characters you can or cannot use

Acceptable characters	Notes
a-z, A-Z, 0-9	You can enter these characters directly or into a special format, like a subscript.
(), []	When you enter the first part, it displays in red until you close the expression.
+, -	Use + (plus sign) in superscripts or in the baseline. Use - (minus sign) in superscripts only.
,	You cannot add a space after a comma.
*	Appears as the multiplication dot in answers, except in superscripts. The letter "x” is reserved for symbolic expressions, such as x+y, so you cannot use it for multiplication.

Some characters are available ONLY for use in keyboard shortcuts. For example: \, /, ^, = *, -, >, and _. For more about shortcuts, choose Keyboard shortcuts from the toolbar.
Tablet or smartphone users: To enter the characters above, open the Letters or Numeric menus on the toolbar.
You cannot enter spaces or periods.
To represent a decimal coefficient, enter its equivalent fraction. For example, enter 1/2 instead of 0.5. See next section for how to enter a fraction.

Insert subscript, superscript, isotope, fraction, overbar, reaction/equilibrium arrow, or dot

To hide the special format buttons available from the open Templates menu: Choose the Close Keyboard button or choose a different menu.

To enter...	Choose this from the Templates menu:	Or, enter this keyboard shortcut:	Examples/Notes (Instead of pressing or below, you can also reposition your cursor.)
Subscript	Tip: The non-subscript part of this icon (base) is shown for reference only. Enter the base before choosing this format.	_ (underbar)	To enter , either: Choose N, choose , and enter 2 Enter: N_2
Superscript (Exponent)	Tip: The non-superscript part of this icon (base) is shown for reference only. Enter the base before choosing this format.	^ (caret)	To enter , either: Choose , enter 63, press , and enter Cu Enter: ^63Cu
Stacked superscript/subscript (for isotopes)		\stack	To enter , either: Choose , type 14, press , enter 7, press , and enter N Enter: \stack147N
Fraction	$fraction template format$	/	To enter , either: Choose $fraction template format$ , enter 2 , press , and enter 3 Enter: 2/3 or /23 To move between the top and bottom parts of a fraction: Use the arrow keys from your computer keyboard or move your cursor using an input device.
Overbar	Tip: The x part of this button is for reference only. Enter the value after you choose the bar format.	\bar	To enter , either: Choose and then choose Enter: \bar\nu
Reaction arrow		-> or --> (\-> and \--> also work)	To enter 2H₂+O₂2H₂O, either: Enter 2H, choose , type 2, press , enter +O, choose , enter 2, press , choose , enter 2H, choose , enter 2, press , and enter O Enter: 2H_2+O_2->2H_2O
Equilibrium arrow		\= or \eq	To enter 2NO₂N₂O₄, either: Enter 2NO, choose , enter 2, press , choose , enter N, choose , enter 2, press , enter O, choose , and enter 4 Enter: 2NO_2\=N_2O_4
Dot		* (asterisk)	To enter Na₂SO₄10H₂O, either: Enter Na, choose , type 2, press , enter SO, choose , enter 4, press , choose , enter 10H, choose , enter 2, press , and enter O Enter: Na_2SO_4*10H_2O

Insert alpha, beta, gamma, and nu

To hide the buttons available from the open Symbols menu: Choose theClose Keyboard button or choose another menu.

To enter...	Choose this format from the Symbols menu	Or, enter this keyboard shortcut
alpha		\alpha
beta		\beta
gamma		\gamma
nu		\nu

Navigate within your answer

The way to move the cursor in an answer depends on whether you are working with a physical keyboard.

Computer users: Use your keyboard arrow keys (, , , ) to move the cursor in your answer. Note that the left and right arrow keys can move the cursor vertically within an expression. You can also use a mouse or other input device to reposition your cursor in an answer, but using the arrow keys may be easier.
Smartphone and tablet users without a physical keyboard: Use your finger or other input device to position the cursor in your answer. For finer cursor control on a phone, enlarge your view of the answer box before moving the cursor. If moving the cursor on your phone is a challenge: Consider completing the question on your computer or tablet.

Stop entering special format values (such as for a subscript) in your answer

When you finish entering a value in a special format (for example, the numerator of a fraction), you need to move the cursor outside of the format area. The way you do this depends on whether you are working with a physical keyboard.

Computer users: Use your keyboard arrow keys (, , , ) to move outside of a special format area in your answer. You can also use a mouse or other input device to reposition your cursor within or outside of a special format, but using the arrow keys may be easier.
Smartphone and tablet users without a physical keyboard: Use your finger or other input device to position your cursor outside of any special format area. For finer cursor control on a phone, enlarge your view of the answer box before moving the cursor. If moving the cursor on your phone is a challenge: Consider completing the question on a computer or tablet.

Comma to separate a series of chemical expressions (no spaces)

Enter a comma and then immediately enter the next expression or formula. You cannot enter any spaces.

Example: CaF₂,CaCl₂,CaBr₂

Edit a chemical notation answer (undo, redo, reset, delete, or copy and paste)

Undo	Choose undo to undo your previous actions in reverse order—one action per click (or tap/touch, on a mobile device). Alternatively, press Ctrl+Z (Windows) or Command-Z (Mac OS) from your computer keyboard.
Redo	Choose redo to redo the previous action. Alternatively, press Ctrl+Y (Windows) or Command-Y (Mac OS) from your computer keyboard.
Reset	Choose reset to clear your workspace. If you want to start over: This is the easiest way!
Delete	Delete button: Deletes individual characters from left to right. You can also use the Delete key on your computer keyboard. For a specially formatted expression (such as a fraction or isotope): Press Delete once to select the item, and then press Delete again to delete it. Backspace key (on a keyboard): Deletes individual characters from right to left. For a specially formatted expression (such as a fraction or isotope): Press Backspace once to select the item, and then press Backspace again to delete it. Keyboard shortcut to cut: You can use standard keyboard shortcuts (Ctrl+X for Windows, Command-X for Mac OS) to cut an answer or parts of an answer. See Step 1 below for details about selecting characters.
Copy and paste	These instructions apply when using a computer. Select the part of the expression you want to copy. To select individual characters or specially formatted expressions (such as a fraction or isotope): Click and drag your input device or hold down the Shift key and press either the left or right arrow key. Continue to press the arrow key for each additional character or format. Copy using a standard keyboard shortcut—Ctrl-C (Windows) or Command-C (Mac OS). Paste using a standard keyboard shortcut—Ctrl-V (Windows) and Command-V (Mac OS).

Open these instructions as you answer questions

Select Help from the toolbar to see these instructions.

Select Keyboard shortcuts for instructions on answering with your keyboard.

Chemical equation or formula questions

Enter chemical equation, formula or expression answers

Move within or edit your chemical equation answers