Contrasting student and scientific views. Dissolving of instant coffee in water seems to be a physical change but in most cases dissolving is accompanied by an energy change and is probably better considered to be a chemical process even though it is possible to recover the original components by physical means.
In fact this should be considered more of a continuum. For example salt dissolving in water is usually considered to be a physical change, however the chemical species in salt solution (hydrated sodium and chlorine ions) are different from the species in solid salt.
Students may believe that beer frothing is an example of a chemical change or an apple ripening is a physical change. Research: Tsaparlis (2003) Students commonly believe that physical changes are reversible while chemical changes are not.
Students also frequently believe that the original substance in a chemical reaction vanishes completely and forever.
· Sulfur hexafluoride (SF6) is not nearly as infamous as CO2, with the latter getting most of the blame for anthropogenic climate change. Yet while measures are being implemented to curb the release …
· Wrap it tightly or transfer it to glass and immerse the glass panel in water (oil and water don’t mix, so this keeps paints wet without dissolving them). Buy a toxic chemical container for all of your oil paint and mineral spirit waste, and …
Imagine an ‘invisible force’ invades the world. Slowly dissolving all life and there’s almost nothing you can do to stop it. And like Thanos, it is inevitable. It sounds like science fiction… yet actually its science non-fiction. Otherwise known as reality and it’s happening right now. I present, ocean acidification, the deranged evil stepchild of Climate Change. Let’s take it back …
· Environmental change, the greenhouse impact, and an Earth-wide temperature boost are three interconnected wonders in earth and environmental science. Truth be told, to comprehend what environmental change is we need to go to the meaning of the greenhouse impact, since it will permit us to see how it meddles with a worldwide temperature alteration.
· Chemistry Assertion Type Questions (Set-1) Ch 6 – Life Processes – Assertion Reasoning Type Questions . Ch7 – Control and Coordination (Assertion-Reasoning Type Questions) Posted by www.eduvictors.in at Monday, March 15, 2021. Email This BlogThis! Share to Twitter Share to Facebook Share to Pinterest.
· A chemical mixture combines two substances that maintain their own properties when combined. H eterogeneous mixtures are made up of a non-uniform composition, while homogeneous mixtures are made up of a uniform composition. For example, water and sand is a heterogeneous mixture — you can easily separate the sand from the water.
Urea is a white crystalline solid organic compound with the chemical formula CO (NH 2) 2. It can be manufactured industrially by the interaction of liquid ammonia and carbon dioxide. It is soluble in water and ethanol but insoluble in ether. It is used mainly for the production of urea formaldehyde resin or plastics and nitrogen containing …
· Q.2. Vapour pressure of a pure liquid X is 2 atm at 300 K. It is lowered to 1 atm on dissolving 1 g of Y in 20 g of liquid X. If molar mass of X is 200, what is the molar mass of Y? (a) 20 (b) 50 (c) 100 (d) 200. Answer Answer: (b) 50
