Final answer:
Potassium fluoride and magnesium bromide undergo a double displacement reaction to form magnesium fluoride (MgF₂), which precipitates, and potassium bromide (KBr), which stays in solution.
Step-by-step explanation:
When Kf and MgBr₂ are reacted in a double displacement reaction, the products formed are magnesium fluoride (MgF₂) and potassium bromide (KBr). In this type of reaction, the cations and anions of the two compounds exchange partners to form two new compounds. Since Kf is not a common chemical notation, assuming it refers to potassium fluoride (KF), we can write the balanced chemical equation for this reaction as follows:
KF (aq) + MgBr₂ (aq) → MgF₂ (s) + 2 KBr (aq)
The potassium (K+) cations will pair with the bromide (Br-) anions, and the magnesium (Mg²+) cations will pair with the fluoride (F-) anions. Magnesium fluoride will likely precipitate as a solid because it is less soluble in water, while potassium bromide will remain in aqueous solution.