g

#O

Stores 297.1 in T; solves

 

/

for P in atmospheres.

 

) 

 

A 5–liter flask contains nitrogen gas. The pressure is 0.05 atmospheres when the temperature is 18°C. Calculate the density of the gas (N 28/V, where 28 is the molecular weight of nitrogen).

Keys:Display:Description:

H

º#/ºº!

N

@

 

) 

.05 g

#@

 

)

5 g

@

 

) 

g

!@

 

 )

18 ‘273.1 ›

!@

 

 )

g

#

 

/

 

)

28 z

)  

Displays the equation. Solves for N; prompts for P.

Stores .05 in P; prompts for V.

Stores 5 in V; prompts for R.

Retains previous R; prompts for T. Calculates T (Kelvins).

Stores 291.1 in T; solves for N.

Calculates mass in grams, N 28.

LV q

) 

Calculates density in

 

 

grams per liter.

Understanding and Controlling SOLVE

SOLVE first attempts to solve the equation directly for the unknown variable. If the attempt fails, SOLVE changes to an iterative(repetitive) procedure. The procedure starts by evaluating the equation using two initial guesses for the unknown variable. Based on the results with those two guesses, SOLVE generates another, better guess. Through successive iterations, SOLVE finds a value for the unknown that makes the value of the equation equal to zero.

Solving Equations 7–5