A car manufacturer wants to determine the effect of weight on gas mileage for a particular model of car. The gas tank of 10 identical cars are filled with the same type of gas. Each car has a different amount of weight in its trunk. Each car is driven at the same pace around a level track for 200 miles. The amount of gasoline left in each tank is measured.

This question is incomplete; it is asking to identify the variables in the experiment.

Independent variable: WEIGHT

Dependent variable: AMOUNT OF GASOLINE

Constants: SAME CARS, SAME TYPE OF GAS, SAME PACE OF DRIVING

Explanation:

In an experiment, the independent variable refers to the variable that is changed or manipulated by the experimenter. In this case, the independent variable is the WEIGHT in the trunk of each car.

The dependent variable is the variable that is measured in an experiment. In this case, the dependent variable is the AMOUNT OF GASOLINE LEFT IN EACH TANK.

The constants are those variables that the experimenter deliberately keeps unchanged or constant throughout the experiment. In this experiment, the constants are SAME CARS, SAME TYPE OF GAS, SAME PACE OF DRIVING.

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol