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1 year ago

List 5 of the signs that can identify the evidence of a chemical change.

Chemistry

1 answer:

trapecia [35]1 year ago

8 0

Answer:

here are some ideas <3

Explanation:

burning of paper.

cooking of food

burning of wood

rotting of fruits.

frying egg

rusting of iron

mixing acid and base.

burning of candle

leaves changing color

melting of sugar.

baking

explosion of fireworks.

souring milk

digestion of food

fermentation

lighting matchstick

photosynthesis

decomposition of waste

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You are given an unknown mixture containing NaCl and NaHCO3. When you carry out the heating exactly as described in part A, only

SOVA2 [1]

Answer:

1.52g NaHCO3 were in the original mixture.

Mass percent: 64.1%

Explanation:

When NaHCO3 heats it descomposition occurs as follows:

2 NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g).

The loss in mass is because of the evaporization of CO2 and H2O. As both are in the same porportion, its molar mass is the sum of both compounds (44g/mol + 18g/mol = 62g/mol)

Loss in mass: 74.80g - 74.24g = 0.56g.

In moles:

0.56g * (1mol / 62g) = 0.00903 moles of gas.

As 1 mole of the gases comes from 2 moles of NaHCO3:

Moles NaHCO3:

0.00903 moles of gas * (2 moles NaHCO3 / 1 mole gas) = 0.018 moles NaHCO3.

In grams (Molar mass NaHCO3: 84g/mol):

0.018 moles NaHCO3 * (84g / mol) = 1.52g NaHCO3 were in the original mixture.

The mass of the mixture was:

74.80g - 72.428g = 2.372g

That means mass percent of NaHCO3 is:

(1.52g / 2.372g) * 100 = 64.1%

7 0

3 years ago

What is the functional group of a carboxylic acid?

Talja [164]

Answer:

A. Carbon double bonded to oxygen and a hydroxyl group (OH).

4 0

2 years ago

You are running a rather large scale reaction where you prepare the grignard reagent phenylmagnesium bromide by reacting 210.14

almond37 [142]

Answer:

We would expect to form 7.35 moles of grignard reagent.

Explanation:

Step 1: Data given

Mass of magnesium = 210.14 grams

Volume bromobenzene = 772 mL

Density of bromobenzene = 1.495 g/mL

Molar mass of Mg = 24.3 g/mol

Molar mass of bromobenzene = 157.01 g/mol

Step 2: The balanced equation

C6H5Br + Mg ⇒ C6H5MgBr

Step 3: Calculate mass of bromobenzene

Mass bromobenzene = density bromobenzene * volume

Mass bromobenzene = 1.495 g/mL * 772 mL

Mass bromobenzene = 1154.14 grams

Step 4: Calculate number of moles bromobenzene

Moles bromobenzene = mass bromobenzene / molar mass bromobenzene

Moles bromobenzene = 1154.14g / 157.01 g/mol

Moles bromobenzene = 7.35 moles

Step 5: Calculate moles of Mg

Moles Mg = 210.14 grams /24.3 g/mol

Moles Mg = 8.65 moles

Step 6: The limiting reactant

The mole ratio is 1:1 So the bromobenzene has the smallest amount of moles, so it's the limiting reactant. It will be completely consumed ( 7.35 moles). Magnesium is in excess, There will react 7.35 moles. There will remain 8.65 - 7.35 = 1.30 moles

Step 7: Calculate moles of phenylmagnesium bromide

For 1 mole of bromobenzene, we need 1 mole of Mg to produce 1 mole of phenylmagnesium bromide

For 7.35 moles bromobenzene, we have 7.35 moles phenylmagnesium bromide

We would expect to form 7.35 moles of grignard reagent.

5 0

2 years ago

imagine that you're able to fully dissolve a powered substance and water what can be said about this creation

Softa [21]

We can say that the water is the solvent, and the powder is the solute. This is also a solution altogether.

Explanation:- A solute is the thing being dissolved into the solvent. While the solvent is what when the solute is being dissolved in. Together, they make a solution.

8 0

2 years ago

In CaSO4, the oxidation number of Ca is that of S is and that of O is

Assoli18 [71]

Answer: In CaF2, the oxidation number of Ca is +2

, and that of F is -1

. In H2SO4, the oxidation number of H is +1

, that of S is +6

, and that of O is -2

. In CaSO4, the oxidation number of Ca is +2

, that of S is +6

, and that of O is -2

. In HF, the oxidation number of H is +1

, and that of F is -1

7 0

2 years ago

List 5 of the signs that can identify the evidence of a chemical change.​

List 5 of the signs that can identify the evidence of a chemical change.