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3 years ago

Which of these is an example of a physical change?

Chemistry

1 answer:

asambeis [7]3 years ago

4 0

Answer:

Physical changes are anything that changes the subject physically (crinkling paper, turning ice into water, or cutting grass) without chemically altering the makeup of the substance (burning, rusting/oxidation, or digestion).

You could think of it as this way: physical changes can be reversed while chemical changes cannot be reversed.

You might be interested in

Can plants grow with different liquids

Pavlova-9 [17]

Yes plants can grow with different liquids

8 0

3 years ago

Write the balanced equation for the reaction of dilute sulfuric acid. H2so4 , with sodium hydroxide

Aleksandr [31]

Answer:

H2SO4 + 2NaOH → Na2SO4 + 2H2O

Explanation:

This question is describing the neutralization reaction between dilute sulfuric acid (H2SO4) and sodium hydroxide (NaOH). These two compounds combine to form sodium salt and water as products (see the chemical equation below).

H2SO4 + NaOH → Na2SO4 + H2O

However, this equation is not BALANCED because the number of atoms of each element are not the same on both sides of the equation. To balance the equation, COEFFICIENTS are used as follows:

H2SO4 + 2NaOH → Na2SO4 + 2H2O

From this equation, the atoms of hydrogen (H), sulphur (S), oxygen (O), sodium (Na) are now equal on both sides, hence, it is said to be BALANCED.

3 0

3 years ago

A 1.87 L aqueous solution of KOH contains 155 g of KOH . The solution has a density of 1.29 g/mL . Calculate the molarity ( M ),

lbvjy [14]

Answer:

[KOH] = 1.47 M

[KOH] = 1.22 m

KOH = 6.86 % m/m

Explanation:

Let's analyse the data

1.87 L is the volume of solution

Density is 1.29 g/mL → Solution density

155 g of KOH → Mass of solute

Moles of solute is (mass / molar mass) = 2.76 moles.

Molarity is mol/L → 2.76 mol / 1.87 L = 1.47 M

Let's determine, the mass of solvent.

Molality is mol of solute / 1kg of solvent

We can use density to find out the mass of solution

Mass of solution - Mass of solute = Mass of solvent

Density = Mass / volume

1.29 g/mL = Mass / 1870 mL

Notice, we had to convert L to mL, cause the units of density.

1.29 g/mL . 1870 mL = Mass → 2412.3 g

2412.3 g - 155 g = 2257.3 g of solvent

Let's convert the mass of solvent to kg

2257.3 g / 1000 = 2.25kg

2.76 mol / 2.25kg = 1.22 m (molality)

% percent by mass = mass of solute in 100g of solution.

(155 g / 2257.3 g) . 100g = 6.86 % m/m

5 0

3 years ago

(4x972)+(76.4x29.3)-(12x7)<br> solve using significant figures please ASAP

mezya [45]

There are 5 rules to significant figures

All non zero numbers are significant

Zeros between 2 non zeros digits are significant

Leading zeros are not significant

Trailing zeros to the right of the decimal are significant

Trailing zeros in a whole number with the decimal shown are significant

The answer is
6042.52

7 0

3 years ago

Read 2 more answers

Rank the following molecules (1st, 2nd, 3rd, 4th) in the order that they melt.

Daniel [21]

Sodium chloride has the highest melting point while iodine has the least melting point.

The melting points of solid substances depends on the nature of intermolecular forces that exists in the substance. The stronger the magnitude of intermolecular forces in a substance, the higher its melting point.

The order of melting points of the solids shown in question is as follows;

1st - Sodium chloride
2nd - sucrose
3rd - paraffin
4th - Iodine

Sodium chloride has the highest melting points because it is an ionic substance. Among the molecular sucrose and paraffin, sucrose has a higher melting point than sucrose because it has a greater molar mass. Iodine, a molecular substance has the least molar mass and the least melting point in the list.

Learn more: brainly.com/question/25777663

6 0

2 years ago