Chem Lab Exam 1

To calculate slope in excel:

= slope(y values, x values)

To calculate y intercept in excel

= intercept(y values, x values)

To calculate average in excel

= average(values)

Standard Deviation=

sqrt (value-average)²+ …/total number-1

Standard deviation function

STDEV.S

slope intercept equation

y=mx+b

Percent Error

(measured value- true value)/true value) *100

Absolute Value

actual value-measured value

100 ml beaker

50 ml graduated cylinder

10 ml volumetric flask

50 ml buret

transfer pipet

10 ml volumetric pipet

analytical balance

Pan balance

50 ml Erlenmeyer Flask

Test tube

How to measure with volumetric pipet

1. Attach bulb to the top

2. Extract liquid to meniscus

3. Transfer liquid

Accuracy

How close measured value is to the true or accepted value

Precision

How consistent the data is within each other

How to calculate accuracy

Absolute Error

How to calculate precision

use standard deviation, smaller value = more precise

Percent Composition in unknown mixtures

mass of component/ total mass of mixture *100

difference between gravitational filter and vacuum filter

• Gravity filter uses gravity to move liquid through the filter

• Vacuum filter uses vacuum to create pressure to draw the liquid through the filter

Theoretical Yield

Determine the moles of element—use molar ratio as converstion factor— Convert mols to grams

Yield Percent

Actual yield/theoretical yield *100

gravity filter

vacuum filter

crucible

bunsen burner

watch glass

Dilution Calculation

M1V1=M2V2

Ideal Gas Law

PV=nRT

R=

0.0821

T=

Kelvin

Celcius to Kelvin: add 273.15

V=

Liters

P=

pressure, atm

n=

moles of gas

M=

mol/L

q=

(specific heat)(mass)(temp change)

Heat lost (qcal)=

qwarm water+ qcold water + qcal= 0

heat capacity=

q/change in temp (J/Celcius)