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3 years ago

Why did Bromophenal solutions change from yellow to blue(what chemical reaction happended)?

1 answer:

6 0

Phenolphthalein Phenolphthalein is a universal indicator, which means it changes color to show the pH of certain solutions. Phenolphthalein stays colorless in acidic solutions and turns pink in alkaline solutions. Sodium hydroxide is a base, so when you add phenolphthalein, the solution turns pink. Other indicators commonly used in the laboratory are litmus and methyl orange. A Litmus indicator solution goes red in acidic solutions, blue in alkaline solutions and purple in neutral solutions. Methyl orange turns red in acidic solutions and yellow in neutral or alkaline solutions.

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A student needs to prepare 100. mL of 0.612 M Cu(NO3)2 solution. What mass, in grams, of copper(II) nitrate should the student u

Temka [501]

Answer: 11.5 grams

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution

$Molarity=\frac{n\times 1000}{V_s}$

where,

Morality = 0.612 M

n= moles of solute

$V_s$ = volume of solution in ml = 100 ml

Now put all the given values in the formula of molarity, we get

$0.612=\frac{n\times 1000}{100ml}$

$n=0.0612moles$

$Mass={\text {moles of solute }}{\times {\text {molar mass}}=0.0612moles\times 187.56g/mol=11.5g$

Therefore, the mass of copper (II)nitrate required is 11.5 grams

3 0

3 years ago

A student placed a stack of rocks on a ramp. She added clumps of soil rooted with live grass. Using a garden hose, she then appl

Sliva [168]

<span>Answer D. Spray from the hose suggests water in liquid state falling into the soil. The process of elimination: A glacier can be related to water in frozen but in static state. B Fast winds has the element of movement of air, not water. C. A hail storm, movement of water in frozen state. D. Heavy rains looks to be better choice compares to the others.</span>

7 0

3 years ago

Read 2 more answers

Directions: Use the words in the word box to complete the following sentences.

NeX [460]

Explanation:

When the forces acting on an object are balanced , there is no change in the object's motion.

A force acting on a resting object can cause the object to move.

On Earth, gravity pulls all objects toward the ground.

When a force acts in the opposite direction of another force, the forces counteract each other.

More than one force acting on a falling object can reduce its downward acceleration

Air resistance is caused by molecules of air pushing against a moving object

7 0

3 years ago

What volume, in milliliters, of a 0.997 M KOH solution is needed to neutralize 30.0 mL of 0.0400 M HCl?

deff fn [24]

Answer:

1.2 mL

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated:

HCl + KOH —> KCl + H₂O

From the balanced equation,

Mole ratio of the acid, HCl (nₐ) = 1

Mole ratio of base, KOH (n₆) = 1

Finally, we shall determine the volume of the base, KOH needed to neutralize the acid, HCl as follow:

Molarity of base, KOH (M₆) = 0.997 M

Volume of acid, HCl (Vₐ) = 30 mL

Molarity of acid, HCl (Mₐ) = 0.0400 M

Volume of base, KOH (V₆) =?

MₐVₐ / M₆V₆ = nₐ/n₆

0.04 × 30 / 0.997 × V₆ = 1/1

1.2 / 0.997 × V₆ = 1

Cross multiply

0.997 × V₆ = 1.2

Divide both side by 0.997

V₆ = 1.2 / 0.997

V₆ = 1.2 mL

Thus, the volume of the base, KOH needed to neutralize the acid is 1.2 mL.

7 0

3 years ago

An arrow is moving at 35m/sand travels for 5 seconds.how far did the arrow travel?

docker41 [41]

Answer:

175 meters

Explanation:

As it's velocity is 35m/s

so,

by formula

35 *5

175 meters

8 0

3 years ago