Chemical reaction which happens when adding vinegar to limestone

Using vinegar is a common method to remove limestone from equipment or tools that are usually submerged in tap water. The chemical reaction that happens when this happens is the following.

CaCO₃ (the limestone) + 2CH₃COOH (the vinegar) → Ca(CH₃COO)₂ (calcium acetate) + H₂O (water) + CO₂ (carbon dioxide)

What can and cannot be recycled

As far as plastic is concerned, every plastic type except for type 3 (PVC) and types 6 (PS) and 7 (Other), can be recycled safely. Which is good.
Types 3, 6, and 7 should not be recycled, ever.

Note: the above only applies to the Romanian recycling system

Source

Side note

As far as carton is concerned, PAP 21 (carton), PAP 22 (paper), PAP 20 (corrugated cardboard) and C/PAP 81 (carton + plastic) and C/PAP 84 (aseptic - carton, plastic, aluminium) can all be sorted as carton packaging.

Source

Composition of human farts

This is just for fun.

More than 99% of the volume of flatus is composed of non-smelly gases. These include oxygen (O₂), nitrogen (N), carbon dioxide (CO₂) hydrogen (H) and methane (CH₄). Keep in mind, methane is a colorless, odorless gas and nitrogen is not produced in the gut, but it is a component of environmental air. The remaining trace (<1% volume) compounds give flatus its smell which comes from a combination of volatile sulfur compounds. Hydrogen sulfide (H₂S), methyl mercaptan (CH₄S), dimethyl sulfide (C₂H₆S), dimethyl disulfide (C₂H₆S₂), and dimethyl trisulfide (C₂H₆S₃).

Breakdown:

hydrogen sulfide

Hydrogen sulfide is a poison that affects nervous system the most. The toxicity of H2S is comparable with that of carbon monoxide as it binds with iron and it prevents cellular respiration.

ethyl mercaptan

It is a colorless but flammable gas with an extremely strong and repulsive smell (rotten egg). At very high concentrations it is highly toxic and affects the nervous system. It is used as an additive in natural gas in order to detect leakage.

dimethyl sulfide

It is flammable and an eye and skin irritant. It has an unpleasant odor at even extremely low concentrations.