Aboard has a mass of 750 g. if you ground the whole board down to sawdust, what would be the mass of the pile of sawdust?

The law of conservation of mass states that mass can neither be created nor destroyed. For example in an isolated system, mass of the reactants is equal to the mass of the products. Thus, mass or the quantity of the system under consideration will remain unchanged through any physical or chemical process.

In the given example, the board initially has a mass of 750 g. It is physical transformed to sawdust by grinding. Based on the conservation of mass, the pile of sawdust would still weigh 750 g.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

window cleaner is ammonia dissolved in water. this is an example of a