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Creating chemPad Answer Keys

When you create your chemPad answer key, use the codes described in the following table. Type spaces where they belong in your notation, such as between quantum levels in an electron configuration and between chemical formulas and arrows or plus signs in reaction equations.  

Note Be sure that your question provides relevant information about assumptions or expectations for the question, for example, the conditions for the question — STP, SATP, or reaction/prevailing conditions — or whether states-of-matter should be specified in the response.
Best Practice Always enclose the contents of superscripts or subscripts in braces {}, even though technically you can omit them when the superscript or subscript includes only numbers and charges.

Expression

Code

Example

Display

Subscript

_ (underscore)

 
H_{2}O

H2O

Superscript

^ (caret) 

Ca^{2+}

Ca2+

Electron configuration

See examples. 

1s^{2} 2s^{2} 2p^{5}
[He] 2s^{2} 2p^{5}

1s2 2s2 2p5

[He] 2s2 2p5

Combining subscripts and superscripts

See examples. 

SO_{4}^{2-}
[Co(SCN)_{2}(H_{2}O)_{4}]
^{+}
^{233}_{91}Pa

SO42-

[Co(SCN)2(H2O)4]+

233 over 91 Pa

Forward reaction arrow

--> 

2 H_{2}O_{2} --> 2 H_{2}O 
+ O_{2}

2 H2O2 → 2 H2O + O2

Equilibrium reaction 

<=>
 
N_{2}(g) + O_{2}(g) <=> 2 
NO(g)

N2(g) + O2(g) ⇌ 2 NO(g)

Reverse reaction arrow 

<--
 
4 NO(g) + O_{2}(g) <-- 
2 N_{2}O_{3}(g)

4 NO(g) + O2(g) ← 2 N2O3(g)

States of matter 

(g)
(l)
(s)
 
CH_{4}(g) + 4 S(s) -->

CS_{2}(l) + 2 H_{2}S(
g)

CH4(g) + 4 S(s) → CS2(l) + 2 H2S(g)

Lowercase Greek letters

The lowercase letter name 

^{0}_{-1}beta
superscript 0 above subscript 1- followed by the Greek letter beta

Uppercase Greek letters

The capitalized letter name 

DeltaH_{f}

ΔHf 

Stacked fraction 

/
 
K_{c} = [COCl] . [Cl] / 
[CO] . [Cl_{2}]
Kc = fraction: [COCl] · [Cl] over [CO] · [Cl2]

Multiplication or solvate dot (·) 

. (period)
 
K_{c} = [COCl] . [Cl] / 
[CO] . [Cl_{2}]
Kc = fraction: [COCl] · [Cl] over [CO] · [Cl2]

Delimiters between items in rank-order questions 

>
<
=
 
K < P < Br

K < P < Br

Delimiters between items in an unordered list 

,
 
HClO, H^{+}, ClO^{-}

HClO, H+, ClO-

Phase boundary, salt bridge (electrochemical cell) 

|, ||
 
Zn(s) | Zn^{2+}(aq) || 
Ag^{+}(aq) | Ag(s)

Zn(s) | Zn2+(aq) || Ag+(aq) | Ag(s)

None (no solution)

(Students enter NONE instead of leaving answer box empty) 

NONE
 
NONE

NONE

As with other Fill-in-the-Blank questions, you can specify multiple correct answers delimited with the {tab} characters. This is most commonly used when you require exact key matching. For example, to allow students to identify chromic acid as either H2CrO4 or H2Cr2O7, your answer key would be: 

H_{2}CrO_{4} {tab} H_{2}Cr_{2}O_{7}