Applying the Techniques of Artificial Intelligence to Chemistry

11 Applying the Techniques of Artificial Intelligence to Chemistry Education 1

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Richard Cornelius , Daniel Cabrol , and Claude Cachet Downloaded by UNIV OF TEXAS AT DALLAS on July 12, 2016 | http://pubs.acs.org Publication Date: April 30, 1986 | doi: 10.1021/bk-1986-0306.ch011

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Department of Chemistry, Lebanon Valley College, Annville, PA 17003 Department of Chemistry, Université de Nice, 06034 Nice, France

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The computer program called GEORGE is a "problem-solving partner" for introductory chemistry students. The program has no problems to present to students; students give problems to GEORGE and he solves the problems. He explains the solution using ordinary English and then sketches a diagram to show how data are combined and relations are applied to give the solution. GEORGE operates on problems involving three fundamental quantities, mass, volume, and number of moles, and other quantities that can be expressed as ratios of these fundamental quantities.

The power o f t h e computer h o l d s t h e promise f o r f a r - r e a c h i n g changes i n e d u c a t i o n , but t h a t promise remains u n r e a l i z e d . Most o f t h e a p p l i c a t i o n s o f computers i n c h e m i c a l e d u c a t i o n have been a d a p t a t i o n s of t e a c h i n g s t r a t e g i e s used i n o t h e r m e d i a ; t h e r e a r e many t a s k s t h a t have been done b e t t e r o r f a s t e r on t h e computer but l i t t l e r e a l l y new has been d e v e l o p e d . There i s a quote t h a t summarizes t h e s i t u a t i o n i n which we f i n d o u r s e l v e s t o d a y : " A f t e r y e a r s o f growing w i l d l y t h e f i e l d o f [ e d u c a t i o n a l ] computing i s f i n a l l y a p p r o a c h i n g i t s i n f a n c y . " T h i s quote i s n e a r l y twenty y e a r s o l d , h a v i n g been t a k e n from t h e r e p o r t o f t h e 1967 P r e s i d e n t ' s S c i e n c e A d v i s o r y Commission (1). The q u o t e , however, i s a s t r u e today a s i t was n e a r l y twenty y e a r s a g o . We s t a n d on t h e t h r e s h o l d o f e x c i t i n g new a p p l i c a t i o n s f o r computers both w i t h i n t h e f i e l d o f e d u c a t i o n and e l s e w h e r e . The s u b j e c t o f t h i s paper i s a computer program w h i c h r e p r e s e n t s one t o t a l l y d i f f e r e n t approach f o r t h e use o f computers i n c h e m i c a l e d u c a t i o n . We hope t h a t i t i s o n l y one new approach o u t o f many t h a t we w i l l see i n t h e f u t u r e . One o f t h e most i m p o r t a n t advantages o f computers i n e d u c a t i o n i s t h e c a p a c i t y o f s o f t w a r e t o a d j u s t t h e pace o r n a t u r e o f a c t i v i t i e s on t h e b a s i s o f i n p u t from t h e s t u d e n t . Tutorial or d r i l l and p r a c t i c e programs a v a i l a b l e today do i n f a c t make some adjustments based upon s t u d e n t r e s p o n s e s . These programs a r e 0097-6156/86/0306-0125$06.00/0 © 1986 American Chemical Society

Pierce and Hohne; Artificial Intelligence Applications in Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1986.

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ARTIFICIAL INTELLIGENCE APPLICATIONS IN CHEMISTRY

l i m i t e d , however, by the i n g e n u i t y o f the person t h a t wrote the s o f t w a r e i n c o n s i d e r i n g a l l p o s s i b l e s t u d e n t r e s p o n s e s and i n d e s i g n i n g a p p r o p r i a t e a c t i o n on t h e p a r t o f the s o f t w a r e . A student cannot e x p l o r e a r e a s which the a u t h o r o f the s o f t w a r e f a i l e d t o consider. Thus, t h e s e programs a r e " i n s t r u c t o r - d r i v e n . " The a u t h o r o f the s o f t w a r e s e r v e s as a s u r r o g a t e i n s t r u c t o r , c r e a t i n g a p a r t i c u l a r sequence o f a c t i v i t é s f o r the s t u d e n t . However s o p h i s t i c a t e d the b r a n c h i n g i n the program may b e , the s t u d e n t cannot t a k e the i n i t i a t i v e ; i n i t i a t i v e i s e x e r c i s e d o n l y by the a u t h o r o f the s o f t w a r e . I t i s u s e f u l t o i d e n t i f y two s o f t w a r e c a t e g o r i e s d i s t i n g u i s h e d by the i d e n t i t y o f the person i n charge o f the e d u c a t i o n a l a c i v i t i e s t h a t the s o f t w a r e s u p p o r t s . The f i r s t c a t e g o r y i s C o m p u t e r - A s s i s t e d Instruction (CAI). I n CAI the r o l e o f t h e s o f t w a r e i s t o d e c i d e w h i c h a c t i v i t i e s the s t u d e n t s h o u l d p u r s u e . Most e x i s t i n g software for chemical education f a l l s i n t o t h i s category. We may a l s o , however, c o n s i d e r a c a t e g o r y o f s o f t w a r e t h a t c o u l d be l a b e l e d C o m p u t e r - A s s i s t e d L e a r n i n g ( C A L ) . I n such s o f t w a r e , the s t u d e n t makes d e c i s i o n s about what he o r she w i l l i n v e s t i g a t e w h i l e u s i n g the software. Simulations f a l l into t h i s category. P r o f e s s o r John G e l d e r ' s i d e a l gas law program (2^ i s a c l a s s i c example o f u s i n g simulations i n chemical education. I n u s i n g t h a t program the s t u d e n t has c o n t r o l o v e r the p a r a m e t e r s , and by e x p l o r i n g the model c o u l d p o t e n t i a l l y l e a r n a s p e c t s o f the b e h a v i o r o f i d e a l gases unknown t o the a u t h o r o f the program. Other s i m u l a t i o n s may a l s o f a l l i n t o the c a t e g o r y o f c o m p u t e r - a s s i s t e d l e a r n i n g . A p a r t from s i m u l a t i o n s , examples o f s o f t w a r e w i t h w h i c h the s t u d e n t i s i n c o n t r o l and a r e d i f f i c u l t to f i n d . T h i s paper d e s c r i b e s an example o f a d i f f e r e n t s t y l e o f program which i s under the c o n t r o l o f the s t u d e n t . The p r o j e c t began i n t h e f a l l o f 1983 when D i c k C o r n e l i u s spent p a r t o f a s a b b a t i c a l a t the U n i v e r s i t é de N i c e w o r k i n g w i t h D a n i e l C a b r o l and Claude C a c h e t . The f i r s t t a s k t h e r e was t o w r i t e a c h a p t e r on microcomputers i n c h e m i c a l e d u c a t i o n f o r a book on computers i n c h e m i s t r y . D u r i n g the c o u r s e o f w r i t i n g t h i s c h a p t e r we d e s c r i b e d programs a v a i l a b l e i n the d i f f e r e n t software s t y l e s : page t u r n e r s , d r i l l and p r a c t i c e , t u t o r i a l d i a l o g s , s i m u l a t i o n , p r e - l a b o r a t o r y a c t i v i t i e s , and p r o b l e m - s o l v i n g . I n t h e a r e a o f p r o b l e m - s o l v i n g , however, t h e r e was l i t t l e t h a t we c o u l d discuss. Some s o f t w a r e c o u l d be used f o r p r o b l e m - s o l v i n g , but t h e r e were no examples o f programs w r i t t e n f o r the p r i m a r y purpose o f helping students learn general problem-solving techniques. I t was t o t h i s a r e a , t h e n , t h a t we t u r n e d our programming a t t e n t i o n . The r e s u l t was a program t h a t we c a l l e d GEORGE ( 3 ) t h a t r u n s on the A p p l e I I s e r i e s o f computers. GEORGE d i f f e r s v e r y much from most programs a v a i l a b l e f o r c h e m i c a l e d u c a t i o n : GEORGE a s k s no q u e s t i o n s o f s t u d e n t s . I n s t e a d , s t u d e n t s t a k e problems t o GEORGE. GEORGE s o l v e s the problems t h a t s t u d e n t s p r o v i d e a n d , most i m p o r t a n t l y , e x p l a i n s the s o l u t i o n s u s i n g both t e x t and d i a g r a m s . If insufficient o r c o n t r a d i c t o r y i n f o r m a t i o n i s a v a i l a b l e , GEORGE can p r o v i d e d i a g n o s t i c comments t o h e l p the s t u d e n t . The domain i n w h i c h GEORGE o p e r a t e s i s a s m a l l but i m p o r t a n t one f o r i n t r o d u c t o r y c h e m i s t r y . He works w i t h problems i n v o l v i n g the fundamental q u a n t i t i e s mass, volume, and number o f m o l e s . He can a l s o work w i t h d e r i v e d q u a n t i t i e s such as d e n s i t y , molar mass, molar


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concentration, etc. The s p e c i f i c q u a n t i t i e s w i t h w h i c h GEORGE can work a r e p r e s e n t e d i n F i g u r e 1. That f i g u r e i s t a k e n from the o n - s c r e e n documentation and a l s o g i v e s the a b b r e v i a t i o n s t h a t s t u d e n t s may use as shorthand t o i d e n t i f y the q u a n t i t i e s t o GEORGE. GEORGE works w i t h the u n i t s g , L , m o l . F o r d e r i v e d q u a n t i t i e s he understands the r a t i o s o f t h e s e u n i t s such as g / L f o r d e n s i t y . He a l s o understands the n u m e r i c a l p r e f i x e s ρ , η , μ, m, c , d , and k . He can work w i t h t h e s e p r e f i x e s i n ^ r a t i o s ^ o f u n i t s such as g/mL o r nmol/raL, and he can a l s o a c c e p t dm o r cm f o r volume.


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The b a s i c approach t h a t GEORGE uses t o s o l v e problems i s d i m e n s i o n a l a n a l y s i s , the same t e c h n i q u e t h a t many o f us use i n our own c l a s s r o o m s t o t e a c h s t u d e n t s how t o s o l v e p r o b l e m s . I n s t e a d o f h a v i n g numerous formulas f o r d i f f e r e n t k i n d s o f p r o b l e m s , GEORGE s i m p l y c o n t a i n s a s e t o f h e u r i s t i c r u l e s which he f o l l o w s t o s e a r c h f o r a s o l u t i o n . One r e s u l t o f u s i n g t h e s e h e u r i s t i c r u l e s i s t h a t he can s o l v e problems never worked by the a u t h o r s o f the program. Another r e s u l t i s t h a t GEORGE may be a b l e t o make p r o g r e s s toward a s o l u t i o n even i f i n c o m p l e t e i n f o r m a t i o n i s a v a i l a b l e . I n such an i n s t a n c e , GEORGE may be a b l e t o respond w i t h a statement such as " I f you c o u l d g i v e me the d e n s i t y o f a l c o h o l , then I c o u l d s o l v e the p r o b l e m . " The r u l e s a r e v e r y s i m p l e i n c o n c e p t . F i r s t GEORGE examines the v a r i o u s p i e c e s o f d a t a a v a i l a b l e . He examines a l l p o s s i b l e p a i r s o f d a t a t o see whether any p a i r can be m u l t i p l i e d o r d i v i d e d t o g i v e i m m e d i a t e l y the s o l u t i o n . I f he cannot f i n d a s o l u t i o n i n t h a t way, he checks t o see whether he can a p p l y a r e l a t i o n t o g e n e r a t e a new p i e c e o f d a t a . I f GEORGE cannot a p p l y a r e l a t i o n , he s e a r c h e s f o r i n t e r m e d i a t e r e s u l t s t h a t might r e p r e s e n t a s t e p toward the s o l u t i o n . GEORGE can s e a r c h f o r two t y p e s o f intermediates. The p r e f e r r e d type i s the r e s u l t o f u n i t s c a n c e l l i n g t o y i e l d a fundamental q u a n t i t y . Thus d i v i d i n g the mass o f a substance by i t s molar mass i s a p r e f e r r e d method t o form an intermediate r e s u l t . L e s s d e s i r a b l e i s the f o r m a t i o n o f an i n t e r m e d i a t e r e s u l t which i s not a fundamental q u a n t i t y but which r e p r e s e n t s i n f o r m a t i o n e x p r e s s e d i n a manner not r e p r e s e n t e d by o t h e r data or i n t e r m e d i a t e s . Each time GEORGE c a l c u l a t e s a new q u a n t i t y , he b e g i n s a g a i n t o l o o k f o r an immediate s o l u t i o n . These a r e a l l the r u l e s t h a t GEORGE needs t o f i n d s o l u t i o n s t o m i l l i o n s o f d i f f e r e n t problem s t a t e m e n t s . The r e s u l t i s u s u a l l y a s o l u t i o n approached i n the same manner t h a t a t e a c h e r might use f o r an e x p l a n a t i o n . The Program The p r i m a r y menu f o r GEORGE i s shown i n F i g u r e 2 . T h i s i s the way t h a t the menu appears when no i n f o r m a t i o n has been g i v e n t o GEORGE; more o p t i o n s a r e a v a i l a b l e a f t e r a problem has been d e f i n e d . To understand how GEORGE o p e r a t e s we w i l l f i r s t c o n s i d e r an o p t i o n t h a t i s o u t s i d e the p r i m a r y t h r u s t o f GEORGE, namely, o p t i o n C , C a l c u l a t e M o l a r Mass. The s t u d e n t sees a s c r e e n which s a y s "Type the f o r m u l a : " There a s t u d e n t may type a f o r m u l a as s i m p l e as NaCl o r more complex such as M g ( C 1 0 , ) . 6 H 0 . GEORGE c a l c u l a t e s the molar mass, e x p l a i n i n g t o the s t u d e n t how the c a l c u l a t i o n i s done as shown z

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Applying AI Techniques to Chemistry Education

i n F i g u r e 3 . The a b i l i t y o f GEORGE t o e x p l a i n what he has done i s the p r i m a r y reason f o r h i s e x i s t e n c e . Other programs, such as TK! S o l v e r (à), have a much l a r g e r domain but f a i l t o e x p l a i n the l o g i c t h a t l e a d s t o the answer. The emphasis w i t h i n GEORGE i s on the s o l u t i o n as a p r o c e s s r a t h e r than upon the answer as a number. L e t us c o n s i d e r next the d a t a page w h i c h i s used t o d e f i n e a p r o b l e m . The f i r s t t a s k f o r the s t u d e n t i s t o i d e n t i f y t h é d e s i r e d quantity. T h i s a c t i o n i s a d e s i r a b l e f i r s t step f o r a student s o l v i n g a problem w i t h o r wihout the a i d o f a computer. GEORGE u n d e r s t a n d s h i s domain. I f a s t u d e n t i d e n t i f i e s " t i m e " as the d e s i r e d q u a n t i t y , GEORGE w i l l respond "Unknown q u a n t i t y . " Each q u a n t i t y needs a l a b e l . S o , f o r example, a s t u d e n t may t e l l GEORGE t o f i n d the mass o f a h a i r . Here " h a i r " i s the l a b e l and i s used by GEORGE i n the d i m e n s i o n a l a n a l y s i s t o determine w h i c h d a t a can be used t o g e t h e r . S t u d e n t s must s p e c i f y a c o n s i s t e n t u n i t . I f mol i s g i v e n as the u n i t f o r the mass o f a h a i r , GEORGE w i l l r e p l y " U n i t does not a g r e e w i t h q u a n t i t y . " The s i m p l e s t k i n d o f problem t h a t GEORGE can work and e x p l a i n i s a m e t r i c u n i t c o n v e r s i o n . F o r example, i f GEORGE i s asked t o f i n d t h e mass o f a h a i r i n m i l l i g r a m s , the s t u d e n t c o u l d s u p p l y on d a t a l i n e A the mass o f t h a t h a i r i n grams. The n u m e r i c a l v a l u e s may be entered i n decimal or e x p o n e n t i a l n o t a t i o n w i t h the e x p o n e n t i a l n o t a t i o n a p p e a r i n g w i t h a s u p e r s c r i p t j u s t as one would w r i t e i t on p a p e r . When GEORGE i s asked t o s o l v e t h i s problem he s t a t e s t h a t the answer was s u p p l i e d i n d a t a l i n e A . T h i s statement i s t r u e , but a s t u d e n t w o r k i n g a u n i t c o n v e r s i o n problem needs t o have a b e t t e r e x p l a n a t i o n . GEORGE d i s p l a y s the worked a r i t h m e t i c showing the u n i t c o n v e r s i o n . An example o f such a d i s p l a y i s shown i n F i g u r e 4 . As an example o f a s l i g h t l y more d i f f i c u l t p r o b l e m , c o n s i d e r a q u e s t i o n w h i c h a s k s f o r the d e n s i t y o f e t h a n o l i n g/mL. A s t u d e n t might p r o v i d e GEORGE w i t h the mass o f a p a r t i c u l a r sample o f e t h a n o l . The mass c o u l d be, f o r example, 25 grams. I f a s t u d e n t t e l l s GEORGE t o s o l v e the problem w i t h o n l y t h i s p i e c e o f i n f o r m a t i o n , he w i l l q u i c k l y r e p l y t h a t he cannot s o l v e the problem w i t h o u t some i n f o r m a t i o n r e l a t e d t o the volume o f e t h a n o l . I f the s t u d e n t then s u p p l i e s the volume o f e t h a n o l , GEORGE e x p l a i n s i n p l a i n E n g l i s h how t o get the answer: " S o l u t i o n found by d i v i d i n g the mass o f e t h a n o l by t h e volume o f e t h a n o l t o g i v e the d e n s i t y o f e t h a n o l . " GEORGE works i n t e r n a l l y w i t h the u n i t s g , L , and m o l . Thus, a f t e r he completes the c a l c u l a t i o n i t i s n e c e s s a r y f o r him t o c o n v e r t the answer t o the u n i t s r e q u e s t e d when the d e s i r e d q u a n t i t y was s p e c i f i e d . A l t h o u g h GEORGE has p r o v i d e d a t e x t u a l e x p l a n a t i o n o f the s o l u t i o n p r o c e s s , i t may be h e l p f u l f o r the s t u d e n t t o see a diagram o f how the p i e c e s o f i n f o r m a t i o n f i t t o g e t h e r . The diagram f o r the problem i n v o l v i n g the d e n s i t y o f e t h a n o l i s shown i n F i g u r e 5. The symbols A and Β i n t h i s diagram r e f e r t o the l i n e s on the d a t a page and a r e f u r t h e r i d e n t i f i e d t o the s t u d e n t when the l e t t e r s A and Β a r e pressed on the keyboard. A s t u d e n t can save problems on the d i s k f o r l a t e r use and t h e d i s k i s i n i t i a l l y s u p p l i e d w i t h a s e t o f complete p r o b l e m s . One example w h i c h comes on the d i s k i n v o l v e s c a l c u l a t i n g the m o l a r i t y o f a n i l i n e i n s o l u t i o n . The a v a i l a b l e d a t a a r e :


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C a l c u l a t e Molar Mass The Holar nass i s 331.297 g/nol. Mg

Applying the Techniques of Artificial Intelligence to Chemistry

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