what is a pure substance made of positive and negative ions in a fixed ratio called (1 point)
a polar molecule
a hydrogen bond
an atom
an ionic compound
an ionic compound
A 50 gram glass holds 400 grams of liquid water and 75 grams of ice. After 20 minutes the mass of ice is 50 grams. Calculate the mass of the liquid water at this point in time using the law of conservation of mass
According to the law of conservation of mass, the total mass of the system should remain constant throughout the process.
Initially, the mass of the glass is 50 grams, the mass of liquid water is 400 grams, and the mass of ice is 75 grams. Thus, the total initial mass is:
50 grams (glass) + 400 grams (liquid water) + 75 grams (ice) = 525 grams
After 20 minutes, the mass of the ice decreased from 75 grams to 50 grams. This means that 25 grams of ice have melted into liquid water.
Therefore, the total mass of the system at this point in time is still:
50 grams (glass) + 400 grams (liquid water) + 50 grams (ice) = 500 grams
To calculate the mass of the liquid water, subtract the mass of the glass and the remaining mass of the ice from the total mass:
500 grams (total mass) - 50 grams (glass) - 50 grams (ice) = 400 grams
Hence, the mass of the liquid water at this point in time is 400 grams.
A pure substance made of positive and negative ions in a fixed ratio is called an ionic compound.
The correct answer is "an ionic compound".
To determine this, we need to understand the characteristics of the given options:
1. A polar molecule: A polar molecule consists of atoms that have an uneven distribution of charge, resulting in a positive and negative end. However, it does not necessarily involve positive and negative ions in a fixed ratio.
2. A hydrogen bond: A hydrogen bond is a weak attraction between a hydrogen atom in one molecule and an electronegative atom in another molecule, such as oxygen or nitrogen. It does not involve positive and negative ions in a fixed ratio.
3. An atom: An atom is the basic unit of matter, consisting of a nucleus containing protons and neutrons, surrounded by electrons. It does not involve positive and negative ions in a fixed ratio.
4. An ionic compound: An ionic compound is composed of positively charged ions (cations) and negatively charged ions (anions) that are held together by electrostatic attractions. They exist in fixed ratios to maintain overall charge neutrality.
From these options, only "an ionic compound" fits the description of a pure substance made of positive and negative ions in a fixed ratio.