## Question:

Discuss About The Density Of Water By Temperature And Unit.

## Answer:

### What is density of water?

Prior to the understanding of the density of water, it is necessary to understand the term density. Density can be termed as the mass per unit volume of any kind of substance. The density of water can be identified as the weight of the water per unit volume that majorly relies on the temperature of the water. The general value that is used for any kind of calculation is one gram per milliliter (1gm/ml) or else one gram per cubic centimeter (1gm/cm^{3}). However, apart from these there is more precise value that can be used in any experiment or calculation. It has noted that the density of the pure water is usually less than one gram per cubic centimeter (1gm/cm^{3}). The value associated with the density of the liquid water is represented by a standard table. It is important to know that, water can be super cooled as well as remain as a liquid well below its normal freezing point. The highest density of water has measured near to 4 degree Celsius. However, the ice has less density as compared to the liquid water, hence it floats. Furthermore, the density can be calculated as the mass of the substance divided by the volume of that substance and the water is used as the fundamental for establishing metric unit of the mass, which again implies that one cubic centimeter of water weighs one gram. However, the exact density of the water always depends upon the temperature or the air pressure of the area. These variations in the density depend on the exact calculation as well as the experiments takes place in the area having extreme temperature or pressure. The water density values are true for the pure water. However, salt water such as the sea water has different density, depending upon the amount of salt dissolved in the water. Moreover, the sea water density is comparatively more than the density associated with the pure water, which is about 1.20 gram per cubic centimeter to 1.30 gram per cubic centimeter. The table below shows the water density for different units.

Unit | Water density |

Density of water g/cm | 1g/cm |

Density of water g/mL | 1g/mL |

Density of water kg/m | 1000 kg/m |

Density of water ib/ft | 62.4 ibs/ft |

(Table 1: Density of water at different units)

### Water density at different temperature

Temperature (°F/°C) | Density of Water (grams/cm |

-22°/-30° | 0.98385 |

-4°/-20° | 0.99355 |

14°/-10° | 0.99817 |

32°/0° | 0.99987 |

39.2°/4.0° | 1.00000 |

40°/4.4° | 0.99999 |

50°/10° | 0.99975 |

60°/15.6° | 0.99907 |

70°/21° | 0.99802 |

80°/26.7° | 0.99669 |

90°/32.2° | 0.99510 |

100°/37.8° | 0.99318 |

120°/48.9° | 0.98870 |

140°/60° | 0.98338 |

160°/71.1° | 0.97729 |

180°/82.2° | 0.97056 |

200°/93.3° | 0.96333 |

212°/100° | 0.95865 |

(Table 2: Density of water at different temperature)

The above table represents the density of water in grams per cubic centimeter at different temperature, starting from below the freezing point of the water that is -22 degree Fahrenheit or -30 degree Celsius to the boiling point of the water that is 212 degree Fahrenheit to 100 degree Celsius. Apart from that, as per the information present in the above table, water has the exact density of 1 gram per cubic centimeter at a temperature of 39.2°F or 4.0°C. However, once the temperature gets below the freezing point of water that is, 32°F/0°C the density of water becomes low as ice possess comparatively less density than the liquid water. This is the only reason of floating of ice on the top of water. In addition to hat, the above table shows that for the temperature of a typical science lab, which is about 50°F/10°C to 70°F/21°C, the water density is almost close to one gram per cubic centimeter. Hence, this value is used for calculating the most appropriate density calculation. However, when the temperature of the water changes from one direction to another in a very extreme condition, in that case the density of 1 g/cm^{3 }is no longer accepted to be accurate.

### How to calculate the density of a substance?

As discussed above, the formula for calculating the density of any substance is the division of the mass of the substance and the volume of that substance, that is, ?=m/v, where, the density of the substance is represented by the symbol ? (pronounced as “Rho”). Depending on the type of object, that is whether it is regularly shaped, irregular or liquid there exists three major way of calculating the density.

### Calculation of density of one regular object

Considering the case of regular objects whose faces are the standard polygons, such as triangles, rectangles, squares and more; calculation of the volume and mass is not complex. The mass of any object is identified by its weight. On the other hand, in order to determine the volume, all the rectangular polygons have different equations depending on their height, width and length. Taking an instance, for calculating the density of a regular rectangular piece of aluminum, weighing 865 grams, having a measurement of 10cm ? 8cm ? 4cm, first it is necessary to calculate the volume of that aluminum piece. To calculate its volume, it is necessary to multiply the length, width and height of the chosen object.

V = 10cm ? 8cm ? 4cm = 320 cm^{3}

Applying the formula of density and dividing the mass and volume,

865g/320cm^{3} = 2.7g/cm^{3}

Therefore, the density of the taken piece of aluminum is calculated to be 2.7g/cm^{3} and regardless, of the size of the aluminum, the value is true for any piece of aluminum.

### Calculation of density of an irregular object or liquid

In case of the irregular object it is easy to find its volume, by simply placing it in any graduated cylinder that is filled with sufficient water and measuring the volume of water it displaces. Moreover, the Archimedes' Principle says that, any object that displaces the volume of a liquid is same as its own volume. After finding the volume of the substance, applying the formula, the density can be calculated. Considering the previous case, if there is any irregular piece of aluminum, that displaces 204 ml of water and weighing 550 gram, the density will be,

? = 550g/204mL = 2.7g/mL.

### Calculation of density of the liquid by the help of Hydrometer

Hydrometer looks same as a thermometer, having a big bulb at its one end in order to make it float. in order to use this, it is necessary to put the hydrometer lower into a liquid, and leave it until it floats on its own. After that, it require to identify which part of that hydrometer is right at surface of the taken liquid and mark the number present in the side of the hydrometer. That will become the density of the substance. Furthermore, it has been noticed that the hydrometer floats higher in comparatively more dense liquid and lower in case of less dense liquid.

### What is the density of water?

The density of water is typically calculated as 1 g/cm^{3} or 1000 kg/m^{3}, until you are conducting the exact calculation or else conducting any kind of experiment in the extreme temperature. However, depending on the outside temperature, the density of the water changes. Hence, while carrying out any experiment near to or past the boiling point or freezing point of the water, it is required to use one different value for measuring the density. Moreover, both of the ice as well as steam have less density as compare to the water. As discussed above, in order to calculate the density measurement of the mass and volume of the substance is necessary. The formula for calculating the density of any substance encompasses the division of the mass and volume of the substance. Furthermore, for measuring the density of substance it is necessary to identify which type of object it is; that is whether it is regularly shaped, irregular or else liquid. In case of the regularly objects it is important to calculate the volume by applying different formulas based on the shape and then proceed forward. However, in case of calculating the density of an irregular object or liquid, it requires measuring the volume of liquid or the amount of liquid that one irregular object displaces in one graduated cylinder. Apart from that, using hydrometer can also become beneficial in measuring the density of a liquid. Therefore, analyzing the entire situation it can be explained that, water does not always possess absolute density as its density always depends on the external temperature and varying in temperature reflects varying in the density of water. At 4 degree Celsius, water has its maximum density, which is 1gram per cubic centimeter (1g/cm^{3}). The density of any substance remains same, regardless of size of the sample taken.