Which of the following is not an indication of a chemical reaction?

Chemistry

2 answers:

lakkis [162]3 years ago

8 0

A substance freezes.

Y_Kistochka [10]3 years ago

3 0

Answer:

A substance freezes

Explanation:

Two substances bursting into flames on contact can be seen as a combustion reaction, and this usually happens with very volatile substances, and is a chemical reaction that changes the substance on the atomic level.

A substance freezing simply demonstrates a phase change, and does not alter the molecule on any level, apart from the arrangement of the atoms.

Bubbles forming when two substances are combined is the indication that a gas has been formed as a product. The only way a gas can be formed is by a chemical change, usually oxygen or hydrogen is given off.

A solid forming is usually named a precipitation reaction, and the solid is called a precipitate, and this is a chemical reaction that forms an insoluble substance.

You might be interested in

Calculate the grams of CaCl2 necessary to make a 0.15M solution.

NNADVOKAT [17]

Answer:

Gram molecular mass = 40 + (35.5)2 = 111g

Mass of $CaCl_2$ in 1 mole = 111g

Mass of $CaCl_2$ in 0.15 mole = 111 × 0.15 = 16.65 g

8 0

3 years ago

குளோரோ பென்சீனை எவ்வாறு பீனால் ஆக மாற்றுவது<br>

Assoli18 [71]

Explanation:

dows method

பதில்: டோவின் முறை

சோடியம் பினாக்ஸைடு அயனியைப் பெற, எதிர்வினை குளோரோபென்சீன் 623K மற்றும் 300atm வெப்பநிலையில் அக்வஸ் சோடியம் ஹைட்ராக்சைடுடன் உயர்த்தப்படுகிறது. சோடியம் பினாக்ஸைடு அயன் அடுத்த கட்டத்தின் போது நீர்த்த எச்.சி.எல் உடன் இணைக்கப்படுகிறது, இது இறுதி தயாரிப்பை பினோலாக உருவாக்குகிறது

by jus dot com

6 0

2 years ago

A hot lump of 115.7 g of an unknown substance initially at 168.3°C is placed in 25.0 mL of water initially at 25.0°C and allowed

marshall27 [118]

The substance has the specific heat capacity of steel and is therefore probably steel.

Let the specific heat of the unknown lump of substance be $c$ .

Energy Exchange = Specific Heat ⨯ Mass ⨯ Temperature Change

Energy the Hot Lump Lost = Energy the Cold Water Gained

Water has a specific heat of $4.2 \; \text{J} \cdot \text{g} ^{-1}\cdot \text{K}^{-1}$ and a density of $1 \; \text{g} \cdot \text{ml}^{-1}$ . 25.0 milliliters of water thus has a mass of 25.0 grams.

$115.7 \times (168.3 - 76.5) \; c = 4.2 \times 25.0 \times (76.5 - 25.0) \\c = 0.51 \; \text{J} \cdot \text{g}^{-1} \cdot \text{K}^{-1}$

Steel has a specific heat of approximately $0.51 \; \text{J} \cdot \text{g}^{-1} \cdot \text{K}^{-1}$ . This substance is thus <em>probably </em>steel.