Which of the following is TRUE? Group of answer choices None of the above is true. The equivalence point is where the amount of acid equals the amount of base during any acid-base titration. An indicator is not pH sensitive. A titration curve is a plot of pH vs. the [base]/[acid] ratio. At the equivalence point, the pH is always 7.

TRUE: The equivalence point is where the amount of acid equals the amount of base during any acid-base titration.

Explanation:

The point on the titration curve where the number of base equivalents added equals the number of acid equivalents is the equivalence point or neutralization point.

Chemical indicators are substances that change color thanks to a chemical change, depending on the pH of the medium, and thus indicate the end point or point of equivalence of an acid-base volumetry.

A titration curve occurs by representing the measured pH as a function of the added volume of titrant, where the rapid change in pH for a given volume is observed. The inflection point of this curve is called the equivalence point and its volume indicates the volume of titrant consumed to fully react with the analyte.

In some cases, there are multiple equivalence points that are multiples of the first equivalence point, as in the valuation of a diprotic acid, which indicates that its pH value will not always be 7.

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