# Create chemPad Questions for Reactions

When you create chemPad questions that are answered with a reaction expression, your students can enter the order of compounds (with their coefficients) differently from the answer key in either the reactants or the products. For example, O2 + CH4  CO2 + H2O is considered equivalent to CH4 + O2  H2O + CO2. Your students can also enter solvate dot notation if needed.

You can choose whether to allow alternative reaction arrows in your students' responses. You can require your students to use the reaction arrow specified in your answer key, allow them to use any reaction arrow, allow either an equilibrium arrow or a right arrow, or allow either an equilibrium arrow or a left arrow.

Note  Do not specify answer keys containing the < or > characters directly in Answer, as these characters might be interpreted as the start or end of a tag. Instead, assign your answer key to a variable and reference the variable as described in this topic.
1. Click Questions > Create. The Question Editor opens.
2. In Name, type a name for the question.
3. In Mode, select Fill-in-the-Blank.
<eqn>
$mykey='answer_key'; '' </eqn> This code assigns your answer key to the variable $mykey. You can use a different variable name if needed.

For example:

Code

CH4 + 2 O2 CO2 + 2 H2O

<eqn>
$mykey='CH_{4} + 2 O_{2} --> CO_{2} + 2 H_{2}O'; '' </eqn> 2 SO2 + O2 2 SO3 <eqn>$mykey='2 SO_{2} + O_{2} <=> 2 SO_{3} ';
''
</eqn>

H3PO4(aq) + 3 NaOH(aq) 3 H2O(l) + Na3PO4(aq)

<eqn>
$mykey='H_{3}PO_{4}(aq) + 3 NaOH(aq) --> 3 H_{2}O(l) + Na_{3}PO_{4}(aq)'; '' </eqn> 4 NO(g) + O2(g) 2 N2O3(g) <eqn>$mykey='4 NO(g) + O_{2}(g) <=>
2 N_{2}O_{3}(g)';
''
</eqn>
5. In Question, type your question. Provide 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. Use the answer placeholder string <_> to specify where the answer box should be displayed.
6. In Answer, type the following items on a single line:
<EQN $PAD='chem';$CHEM='method'; $mykey> where method is one of the following chemPad parsing methods: Reaction Type Allowed Reaction Arrows Method Any Only the reaction arrow specified by the answer key. rxn Equilibrium or or rxn,equ Product-favored or rxn,eqr Reactant-favored or rxn,eql For example: Answer Code CH4 + 2 O2 CO2 + 2 H2O <EQN$PAD='chem'; $CHEM='rxn';$mykey>

2 SO2 + O2 2 SO3

<EQN $PAD='chem';$CHEM='rxn,equ'; $mykey> H3PO4(aq) + 3 NaOH(aq) 3 H2O(l) + Na3PO4(aq) <EQN$PAD='chem'; $CHEM='rxn,eqr';$mykey>

4 NO(g) + O2(g) 2 N2O3(g)

<EQN $PAD='chem';$CHEM='rxn,eql'; $mykey> By default, your students must specify each chemical formula exactly as listed in your answer key. To allow specific kinds of notation, you can add a comma and one of the following methods after rxn, rxn,equ, rxn, eqr, or rxn,eql: Notation Example Method Formula elements in any order CH4N2O or CN2H4O fmla Condensed formulas (NH2)2CO or CH4N2O fmla,index Nuclear particles and nuclides ${}_{1-}{}^{0}\text{β}$ or ${}_{1-}{}^{0}\text{e}$ nclr Nuclear particles with charges nclr,ion Ion charges Mg2+ or Mg+2 ion Ionizable protons first CH3CO2H or HCH3CO2 ion,acid For example: <EQN$PAD='chem'; $CHEM='rxn,equ,fmla,index';$mykey> 
Note
• You do not need to specify the solvate mode for your students to enter solvate dot notation.
• Specify methods only in the order listed here.
• If an answer extends beyond the right side of the Answer box, it is wrapped to the next line, but it is still considered a single line so long as you do not press ENTER.
• As with other fill-in-the-blank questions, you can specify alternative answer keys separated by the characters {tab}. For example:
<EQN $PAD='chem';$CHEM='rxn'; $mykey> {tab} <EQN$mykey2>
7. Optional: Type a Solution.

The solution helps your students understand the steps they need to take to determine the correct answer to the question. Your assignment settings specify when to show the solution.

8. Click Test/Preview to test the appearance and behavior of the question. See Test Questions.
9. Click Redisplay to show certain kinds of errors in the Display section of the Question Editor. Make any needed changes to your question.
10. Optional: Click Show Additional Information and change the question's sharing permission or add descriptive information.
• By default, other instructors can use your question only if you provide them with the question ID, and only you can edit the question or find it in search results. To change the permission, see Share Questions With Other Instructors.
• If you make your question publicly available, you might want to provide descriptive information to help others search for it. See Add Search Metadata to Questions.
11. When your question displays and functions correctly, click Save.

WebAssign assigns it a unique question ID (QID), which is displayed in parentheses after the question name.

You can use your question in an assignment and see it in your My Questions list only after it is saved.

 QID 1534317 Template2 5.CHEMP.07. Fill-in-the-Blank  $mykey='2 HCl + CaCO_{3} --> CaCl_{2} + CO_{2} + H_{2}O'; '' Show the reaction between hydrochloric acid and calcium carbonate that produces calcium chloride, water, and carbon dioxide. ( Omit states-of-matter in your answer.) <_>  ## Example chemPad Question (Reaction) The following table summarizes an actual question.  QID 1534332 Template2 5.CHEMP.08. Fill-in-the-Blank $mykey='C_{5}H_{5}N(aq) + H_{2}O(l) <=> C_{5}H_{5}NH^{+}(aq) + OH^{-}(aq)'; '' Write the reaction for pyridine, C_5H_5N, acting as a base in water. ( Include states-of-matter under SATP conditions in your answer.)
<_> 
 QID 1534326 Template2 5.CHEMP.09. Fill-in-the-Blank  \$mykey='^{131}_{53}I --> ^{0}_{-1}beta + ^{131}_{54}Xe'; '' Write the nuclear equation for beta decay of Iodine-131. ( Omit states-of-matter in your answer.)
<_>